Dickinson College

Scatter hoarding black-capped chickadees use memory to relocate hidden food, often after delays of hours or days. The ability of these birds to maintain accurate memories of the location and current status of many food caches while engaging in other distracting daily activities suggests that their memory may be especially resistant to competing cognitive load. We measured resistance to competing cognitive load during spatial memory tests in black-capped chickadees (Poecile atricapillus) and a non-caching species, dark-eyed juncos (Junco hyemalis). Birds were presented with two types of task. In the Discrimination task, birds learned by trial-and-error to select a target from among 2 distractors. In the Match-to-Sample task, birds viewed a sample which they had to remember in order to correctly select it from among two distractors at test. On two-thirds of trials, the tasks were presented Stand-Alone: after birds initiated a trial, they completed either a Discrimination or a Match-to-Sample task. The remaining trials were Concurrent causing a competing cognitive load: after birds intiated a trial, they saw the sample for the Match-to-Sample task, then completed a Discrimination during the retention interval, and finally completed a Match-to-Sample test. Competing cognitive load reduced accuracy of juncos significantly more than accuracy of chickadees. The need to encode and retain the locations of multiple food caches may have led to the evolution of enhanced cognitive control of memory in black-capped chickadees.

One of the challenges for bryozoans is to avoid refiltering water that has already had its plankton removed. Larger colonies develop colony-wide maculae-centered feeding currents to avoid refiltering water and generally have elevated maculae (monticules). We hypothesize that the height and density of spacing of monticules are inversely proportional to curvature of the colony surface. Larger, flatter colonies should have higher and more closely spaced monticules. We compare two Permian stenolaemate bryozoans whose colonies form branches with elliptical cross sections: the smaller and more elliptical cystoporate Evactinostella crucialis (Hudleston, 1883) from Western Australia (N = 17) and the larger and flatter trepostome Tabulipora sp. from eastern North Greenland (N = 15). Using calipers and digital elevation models, we measured curvature, monticule height, and number of monticules per area. Results indicate that Evactinostella branches are at least twice as curved as those of Tabulipora , their monticules are half the height of Tabulipora , and their monticules are 22% less densely spaced than those of Tabulipora . In Evactinostella colonies, surface curvature is inversely proportional to monticule height and spatial density, which is not true for Tabulipora . Therefore, we conclude that the smaller and more curved the colony surface, the less the colony needs robust colony-wide feeding currents created by tall, closely spaced monticules.

Numerous declines have been documented across insect groups, and the potential consequences of insect losses are dire. Butterflies are the most surveyed insect taxa, yet analyses have been limited in geographic scale or rely on data from a single monitoring program. Using records of 12.6 million individual butterflies from >76,000 surveys across 35 monitoring programs, we characterized overall and species-specific butterfly abundance trends across the contiguous United States. Between 2000 and 2020, total butterfly abundance fell by 22% across the 554 recorded species. Species-level declines were widespread, with 13 times as many species declining as increasing. The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.

Internationally, there has been a decline in the use of juvenile legal facilities (Puzzanchera et al., 2022). Yet, it is well documented that the process of reentering the community following placement in these settings presents numerous challenges for young people. Resilience-focused research offers a critical framework for prevention and intervention efforts to promote positive youth development; however, limited attention is given to the resilience of young people reentering communities from carceral and residential facilities. Addressing this gap in empirical knowledge requires an understanding of existing research on youth reentry and resilience. This scoping review identified peer-reviewed research from the past 20 years that focuses on the resilience of young people reentering from juvenile legal facilities, with a special interest in the subpopulations and identity groups represented and underrepresented in this research area. We identified, synthesized, and appraised 75 international and multidisciplinary studies on resilience experienced by youth who reenter from juvenile legal facility settings. Utilizing the Resilience Portfolio Model (Grych et al., 2015), we classified resilience processes relevant to youth reentry, including: (a) regulatory processes such as coping strategies and motivation; (b) meaning-making strengths such as sense of self, cultural identity, and future orientation; and (c) interpersonal relationships and social ecology, such as educational and vocational support. The utility of this scoping review includes identifying opportunities for future study on the role of resilience for system-involved young people, as well as a translational discussion of implications for existing and future practice, policy, and research in juvenile and criminal legal systems.

The emergence of generative AI (GenAI) has illustrated that higher education needs to adapt to the technology. Its speed of evolution requires that we adequately prepare students for an ever-changing landscape. Toward achieving that aim, we draw on the concept of interpretive flexibility, where the interpretations, uses, and outcomes of a new technology can differ and evolve over time, often with dominant stakeholders controlling the process. To engage marketing students in this process, we propose that they be presented with these diverse interpretations now as part of GenAI literacy. Specifically, we offer three small-scale pedagogical interventions designed to address this urgent need. Given the newness of GenAI, our interventions are designed to be infused into existing marketing instruction, instead of requiring a redesign of a curriculum. With each intervention, students not only significantly decrease their confidence in the accuracy of what GenAI produces but also see reasons to examine the implications of it. Both these outcomes, we suggest, could help to maintain interpretive flexibility required to properly respond to and guide the technology as its uses, impacts, and evolution become evident. We encourage educators to prioritize a comprehensive notion of GenAI literacy in their pedagogy to maintain interpretive flexibility.

Abstract Peru has promoted the use of an intercultural approach as a cornerstone to reduce maternal mortality. The Intercultural Birth Policy was introduced in 2005 to ensure that Indigenous women give birth at a health facility, where doctors could save their lives in the case of an obstetric emergency. Intercultural health policies have at their heart the right of Indigenous people to receive health services that are respectful and cognizant of their medical knowledges and practices, and aim to challenge the subordinate position of Indigenous cultures. Through a qualitative study conducted in 2023 in the Peruvian Amazon, we explored the challenges and limitations of the implementation of this policy two decades after its introduction. We found a superficial and instrumental understanding of the policy by health workers, with the cultural adaptation of maternal care seen as a favor, not a right. Indigenous women experience discrimination and disdain towards their medical practices, which alienates them from the services to which they are entitled. Abstract (SPANISH) El Perú ha promovido desde hace más de dos décadas el uso del enfoque intercultural como una medida clave para la reducción de la mortalidad maternal. La Norma Técnica para la atención del parto vertical con adecuación intercultural se introdujo en el 2005 para garantizar que las mujeres indígenas den a luz en un centro de salud, donde los médicos puedan salvarles la vida en caso de una emergencia obstétrica. Las políticas de salud intercultural tienen como elemento central el derecho de los pueblos indígenas a recibir servicios de salud que sean respetuosos y que reconozcan la validez de sus conocimientos y prácticas médicas. Además, estas políticas apuntan a desafiar la posición subordinada de las culturas indígenas y sus prácticas médicas. A través de un estudio cualitativo realizado en el 2023 en la Amazonía peruana, exploramos los desafíos y limitaciones de la implementación de esta política dos décadas después de su introducción. Nuestros resultados indican que hay una comprensión superficial e instrumental de la política por parte de los trabajadores de la salud. La adaptación cultural del cuidado materno se ve como un favor, no como un derecho. Las mujeres indígenas sufren discriminación hacia sus prácticas médicas, lo que las aleja de los servicios a los que tienen derecho.

This research employs a two-regime threshold quantile autoregressive model with exogenous variables and a GARCH specification to investigate the dynamic relationship between perceived uncertainty and realized equity volatility. By utilizing Twitter-based and newspaper-based economic uncertainty measures, this paper offers insights into S&P 500 market dynamics across multiple distinct scenarios. The switching mechanism is governed by the previous day’s return. We make inferences and model selection within a Bayesian framework for each quantile level and utilize the multiple-try Metropolis algorithm to sample the threshold value, while other parameters are generated based on an adaptive Markov chain Monte Carlo (MCMC) procedure. Our diagnostic checking supports the proposed Bayesian methods. Findings reveal that these indicators capture various facets of uncertainty and display diverse behavior in stable and volatile markets. Specifically, the daily news-based economic policy uncertainty indicator shows a pronounced positive impact on realized volatility in the lower regime at higher quantile levels, while the Twitter-based market uncertainty indicator positively affects realized volatility across all quantile levels in the upper regime. The model selection results suggest that the news-based indicator outperforms other indicators at higher quantile levels, which correspond to more volatile market conditions, while the Twitter-based indicator serves as an effective explanatory variable when the S&P 500 is in a dormant or rising market. This paper presents the innovative use of Twitter-based and news-based indicators as dual proxies for economic uncertainty.

Identifying early indicators of volcanic eruptions is a fundamental part of natural hazard management but is notoriously difficult. Here we consider whether monitoring changes in glacier velocity can help. We use satellite images to investigate changes in the surface velocity of Cone Glacier (Alaska) between November 2017 and January 2022, a period encompassing two eruptions of Mount Veniaminof on which the glacier sits. Our data show high glacier velocities months prior to these eruptions and low velocities immediately before, during and after the 2018 eruption, likely caused by volcanically triggered ice melt and associated changes in subglacial water pressures. Evidence for elevated velocities months prior to eruptions is particularly important and indicates that glacier speed-up might be an early indicator of volcanic unrest. Thus, glaciers could serve as tools for volcano monitoring and eruption forecasting since more than 2500 glaciers globally are located within 5 km of an active volcano.

Gender and humor have always been intimately related. In many societies, comedy is traditionally understood as a masculine pursuit, and women’s existence in comedic spaces has been subject to intense scrutiny by male commentators. Africa’s burgeoning stand-up comedy scene is an important site of contestation in this regard, but in recent years social media has afforded opportunities for African women to bypass traditional industry gatekeepers. In online spaces like Instagram, TikTok, and X (Twitter), African women creators have built massive audiences that cross national and continental boundaries. In this project, I draw on interviews with three prominent female comedy creators—Stella Dlangalala, Thenjiwe Mosely, and Beverly Adaeze—and use their work to shed light on how female comedians negotiate their position(s) in digital spaces rooted in Nigeria, South Africa, the United States, the United Kingdom, and beyond. While social media affords autonomy to performers, success as a comedian-influencer demands more from women than jokes. Feminism, Afropolitanism, and commodification intertwine in the stories of these performers. The gendered body, viewed through the lens of parasocial intimacy that short-form video facilitates, emerges as a site of great significance. In addition, I argue for greater critical attention to what I call “algorithmic mystery”—the influence of opaque social media algorithms in promoting, maintaining, and severing digital connections.

Viviparous snakes may be particularly vulnerable to predicted increases in drought due to the high hydric costs associated with embryonic development, gestation, and their reliance on limited free-standing bodies of water or rain events for hydration. Drought will have negative implications for viper populations if females become increasingly water-stressed and resorb developing embryos to conserve bodily water. We conducted a study to investigate the importance of drinking water in late-term pregnancy and its effect on cutaneous evaporative water loss (CEWL). We measured hydration and water loss in response to supplemental hydration during the final stages of embryonic development and gestation in arid-adapted Prairie Rattlesnakes (Crotalus viridis). Our goal was to assess how supplemental water affects hydration status and water loss (via CEWL) of females during and after pregnancy, and of their neonates before and after their first ecdysis. Supplemental hydration of pregnant C. viridis improved their hydration state and their neonates were also born more hydrated than those from control mothers, showing that they transfer water to neonates via the placenta even over a very short period in the late stages of pregnancy. The supplementally hydrated maternal C. viridis experienced slightly higher rates of CEWL compared to control snakes, but CEWL was primarily driven by ambient temperature and vapor pressure deficit at the time of measurement. At birth, neonate plasma osmolality and CEWL were both directly associated with their mothers’ plasma osmolality and CEWL. Additionally, we found that neonate CEWL increased after the first ecdysis, suggesting that natal skin may help neonates avoid desiccation. Investigating and quantifying physiological implications of water shortage and dehydration can help us better understand the effects of drought and predict how wild populations of arid-adapted reptiles may respond to the predicted increase in frequency and severity of droughts.

This study quantifies the prevalence of a rarely documented occurrence of bryozoans encrusting fossil brachyuran crabs. Over 500 crab fossils were examined from the reef facies of the Rákos Limestone Member of the Leitha Limestone Formation in the quarry at Diósd, Hungary. They were deposited in the upper part of the regional Badenian stage (i.e., lower part of the international Serravallian stage) of the middle Miocene. Nine bryozoan colonies were found encrusting five dorsal carapaces of three different crab species: Panopeus wronai , Dromia neogenica , and Cancer styriacus . The bryozoans were restricted to the exterior surface of the preserved carapaces of the host crabs, so the epibiosis was most likely syn-vivo . The prevalence was calculated at 1%. The bryozoans were all cheilostome gymnolaemates identified as a cribrilinid, a calloporid, Onychocella ? sp., and two indeterminate membraniporiform species. The low prevalence of bryozoan-encrusted crabs is consistent with other fossil-based bryozoan-crab studies but much lower than similar studies in today’s faunas. This discrepancy was attributed to both colony spalling-induced preservational bias and differences in carapace size. The bryozoan-crab symbiosis was described as phoretic hitchhiking.