Showing papers by "DePaul University published in 2020"

Post-viral fatigue and COVID-19: lessons from past epidemics

Abstract: The COVID-19 pandemic, resulting from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has severely impacted the population worldwide with a great mortality rate The current article r

Containment beyond detention: The hotspot system and disrupted migration movements across Europe:

Abstract: This article deals with the ways in which migrants are controlled, contained and selected after landing in Italy and in Greece, drawing attention to strategies of containment aimed at disciplining mobility and showing how they are not narrowed to detention infrastructures. The article starts by tracing a genealogy of the use of the term ‘hotspot’ in policy documents and suggests that the multiplication of hotspots-like spaces is related to a reconceptualisation of the border as a critical site that requires prompt enforcement intervention. The article moves on by investigating the mechanisms of partitioning, identification and preventive illegalisation that are at stake in the hotspots of Lampedusa and Lesbos. Hotspots are not analysed here as sites of detention per se: rather, the essay turns the attention to the channels of forced mobility that are connected to the Hotspot System, focusing in particular on the forced transfers of migrants from the Italian cities of Ventimiglia and Como to the hotspot of Taranto. The article concludes by analysing channels of forced mobility in the light of the fight against ‘secondary movements’ that is at the core of the current European Union’s political agenda, suggesting that further academic research could engage in a genealogy of practices of migration containment.

The pervasive and multifaceted influence of biocrusts on water in the world's drylands.

Abstract: The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (-40%) and commence runoff (-33%), and reduced infiltration (-34%) and sediment production (-68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (-56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier.

Populating the Upper Black Hole Mass Gap through Stellar Collisions in Young Star Clusters

Abstract: Theoretical modeling of massive stars predicts a gap in the black hole (BH) mass function above ~40–50 M_⊙ for BHs formed through single star evolution, arising from (pulsational) pair-instability supernovae (PISNe). However, in dense star clusters, dynamical channels may exist that allow construction of BHs with masses in excess of those allowed from single star evolution. The detection of BHs in this so-called "upper-mass gap" would provide strong evidence for the dynamical processing of BHs prior to their eventual merger. Here, we explore in detail the formation of BHs with masses within or above the pair-instability gap through collisions of young massive stars in dense star clusters. We run a suite of 68 independent cluster simulations, exploring a variety of physical assumptions pertaining to growth through stellar collisions, including primordial cluster mass segregation and the efficiency of envelope stripping during collisions. We find that as many as ~20% of all BH progenitors undergo one or more collisions prior to stellar collapse and up to ~1% of all BHs reside within or above the pair-instability gap through the effects of these collisions. We show that these BHs readily go on to merge with other BHs in the cluster, creating a population of massive BH mergers at a rate that may compete with the "multiple-generation" merger channel described in other analyses. This has clear relevance for the formation of very massive BH binaries as recently detected by the Laser Interferometer Gravitational-Wave Observatory/Virgo in GW190521. Finally, we describe how stellar collisions in clusters may provide a unique pathway to PISNe and briefly discuss the expected rate of these events and other electromagnetic transients.

The Connection Between Popularity Bias, Calibration, and Fairness in Recommendation

Abstract: Recently there has been a growing interest in fairness-aware recommender systems including fairness in providing consistent performance across different users or groups of users. A recommender system could be considered unfair if the recommendations do not fairly represent the tastes of a certain group of users while other groups receive recommendations that are consistent with their preferences. In this paper, we use a metric called miscalibration for measuring how a recommendation algorithm is responsive to users’ true preferences and we consider how various algorithms may result in different degrees of miscalibration for different users. In particular, we conjecture that popularity bias which is a well-known phenomenon in recommendation is one important factor leading to miscalibration in recommendation. Our experimental results using two real-world datasets show that there is a connection between how different user groups are affected by algorithmic popularity bias and their level of interest in popular items. Moreover, we show that the more a group is affected by the algorithmic popularity bias, the more their recommendations are miscalibrated.

Ten simple rules for building an antiracist lab.

Abstract: Demographics of the science, technology, engineering, and mathematics (STEM) workforce and student body in the US and Europe continue to show severe underrepresentation of Black, Indigenous, and people of color (BIPOC). Among the documented causes of the persistent lack of diversity in STEM are bias, discrimination, and harassment of members of underrepresented minority groups (URMs). These issues persist due to continued marginalization, power imbalances, and lack of adequate policies against misconduct in academic and other scientific institutions. All scientists can play important roles in reversing this trend by shifting the culture of academic workplaces to intentionally implement equitable and inclusive policies, set norms for acceptable workplace conduct, and provide opportunities for mentorship and networking. As scientists are increasingly acknowledging the lack of racial and ethnic diversity in science, there is a need for clear direction on how to take antiracist action. Here we present 10 rules to help labs develop antiracists policies and action in an effort to promote racial and ethnic diversity, equity, and inclusion in science.

Feedback Loop and Bias Amplification in Recommender Systems

Abstract: Recommendation algorithms are known to suffer from popularity bias; a few popular items are recommended frequently while the majority of other items are ignored. These recommendations are then consumed by the users, their reaction will be logged and added to the system: what is generally known as a feedback loop. In this paper, we propose a method for simulating the users interaction with the recommenders in an offline setting and study the impact of feedback loop on the popularity bias amplification of several recommendation algorithms. We then show how this bias amplification leads to several other problems such as declining the aggregate diversity, shifting the representation of users' taste over time and also homogenization of the users experience. In particular, we show that the impact of feedback loop is generally stronger for the users who belong to the minority group.

Addressing inequities in COVID-19 morbidity and mortality: research and policy recommendations.

Abstract: The COVID-19 pandemic is the greatest global public health crisis since the 1918 influenza outbreak. As of early June, the novel coronavirus has infected more than 6.3 million people worldwide and more than 1.9 million in the United States (US). The total number of recorded deaths due to COVID-19 are growing at an alarming rate globally (³383,000) and nationally (³109,000) Evidence is mounting regarding the heavier burden of COVID-19 infection, morbidity, and mortality on the underserved populations in the US. This commentary focuses on this global health pandemic and how mitigation of the virus relies heavily on health behavior change to slow its spread, highlighting how the pandemic specifically affects the most socially and economically disadvantaged populations in the US. The commentary also offers short, intermediate and long-term research and policy focused recommendations. Both the research and policy recommendations included in this commentary emphasize equity-driven: (1) research practices, including applying a social determinants and health equity lens on monitoring, evaluation, and clinical trials activities on COVID-19; and (2) policy actions, such as dedicating resources to prioritize high-risk communities for testing, treatment, and prevention approaches and implementing organizational, institutional, and legislative policies that address the social and economic barriers to overall well-being that these populations face during a pandemic. It is our hope that these recommendations will generate momentum in delivering timely, effective, and lifesaving changes.

Feedback Loop and Bias Amplification in Recommender Systems

Abstract: Recommendation algorithms are known to suffer from popularity bias; a few popular items are recommended frequently while the majority of other items are ignored. These recommendations are then consumed by the users, their reaction will be logged and added to the system: what is generally known as a feedback loop. In this paper, we propose a method for simulating the users interaction with the recommenders in an offline setting and study the impact of feedback loop on the popularity bias amplification of several recommendation algorithms. We then show how this bias amplification leads to several other problems such as declining the aggregate diversity, shifting the representation of users' taste over time and also homogenization of the users. In particular, we show that the impact of feedback loop is generally stronger for the users who belong to the minority group.

Differences In Starting Pay For Male And Female Physicians Persist; Explanations For The Gender Gap Remain Elusive

Abstract: A large literature has documented differences in salary between male and female physicians. While few observers doubt that women earn less, on average, than men do, the extent to which certain factors contribute to the salary difference remains a topic of considerable debate. Using ordinary least squares regression and Oaxaca-Blinder decomposition models for new physicians who accepted positions in patient care for the years 1999-2017, we examined how the gender gap in total starting pay evolved and the extent to which preferences in work-life balance factors affect the gap. We found that the physician earnings gap between men and women persisted over the study period. Interestingly, despite important gender differences in preferences for control over work-life balance, such factors had virtually no ability to explain the gender difference in salary. The implication is that there remain unmeasured factors that result in a large pay gap between men and women.

Trait-based aerial dispersal of arbuscular mycorrhizal fungi.

Abstract: Dispersal is a key process driving local-scale community assembly and global-scale biogeography of plant symbiotic arbuscular mycorrhizal (AM) fungal communities. A trait-based approach could improve predictions regarding how AM fungal aerial dispersal varies by species. We conducted month-long collections of aerial AM fungi for 12 consecutive months in an urban mesic environment at heights of 20 m. We measured morphological functional traits of collected spores and assessed aerial AM fungal community structure both morphologically and with high-throughput sequencing. Large numbers of AM fungal spores were present in the air over the course of one year and these spores exhibited traits that facilitate aerial dispersal. Measured aerial spores were smaller than average for Glomeromycotinan fungi. Trait-based predictions indicate that nearly 1/3 of described species from diverse genera demonstrate the potential for aerial dispersal. Diversity of aerial AM fungi was relatively high (20 spore species and 17 virtual taxa) and both spore abundance and community structure shifted temporally. The prevalence of aerial dispersal in AM fungi is perhaps greater than previously indicated and a hypothesized model of AM fungal aerial dispersal mechanisms is presented. Anthropogenic soil impacts may liberate AM fungal propagules initiating the dispersal of ruderal species.

Populating the upper black hole mass gap through stellar collisions in young star clusters

Abstract: Theoretical modeling of massive stars predicts a gap in the black hole (BH) mass function above $\sim 40-50\,M_{\odot}$ for BHs formed through single star evolution, arising from (pulsational) pair-instability supernovae. However, in dense star clusters, dynamical channels may exist that allow construction of BHs with masses in excess of those allowed from single star evolution. The detection of BHs in this so-called "upper-mass gap" would provide strong evidence for the dynamical processing of BHs prior to their eventual merger. Here, we explore in detail the formation of BHs with masses within or above the pair-instability gap through collisions of young massive stars in dense star clusters. We run a suite of 68 independent cluster simulations, exploring a variety of physical assumptions pertaining to growth through stellar collisions, including primordial cluster mass segregation and the efficiency of envelope stripping during collisions. We find that as many as $\sim20\%$ of all BH progenitors undergo one or more collisions prior to stellar collapse and up to $\sim1\%$ of all BHs reside within or above the pair-instability gap through the effects of these collisions. We show that these BHs readily go on to merge with other BHs in the cluster, creating a population of massive BH mergers at a rate that may compete with the "multiple-generation" merger channel described in other analyses. This has clear relevance for the formation of very massive BH binaries as recently detected by LIGO/Virgo in GW190521. Finally, we describe how stellar collisions in clusters may provide a unique pathway to pair-instability supernovae and briefly discuss the expected rate of these events and other electromagnetic transients.

Predicting future from past: The genomic basis of recurrent and rapid stickleback evolution

Abstract: Similar forms often evolve repeatedly in nature, raising longstanding questions about the underlying mechanisms. Here we use repeated evolution in sticklebacks to identify a large set of genomic loci that change recurrently during colonization of new freshwater habitats by marine fish. The same loci used repeatedly in extant populations also show rapid allele frequency changes when new freshwater populations are experimentally established from marine ancestors. Dramatic genotypic and phenotypic changes arise within 5-7 years, facilitated by standing genetic variation and linkage between adaptive regions. Both the speed and location of changes can be predicted using empirical observations of recurrence in natural populations or fundamental genomic features like allelic age, recombination rates, density of divergent loci, and overlap with mapped traits. A composite model trained on these stickleback features can also predict the location of key evolutionary loci in Darwin’s finches, suggesting similar features are important for evolution across diverse taxa.

Mast seeding patterns are asynchronous at a continental scale.

Abstract: Resource pulses are rare events with a short duration and high magnitude that drive the dynamics of both plant and animal populations and communities1. Mast seeding is perhaps the most common type of resource pulse that occurs in terrestrial ecosystems2, is characterized by the synchronous and highly variable production of seed crops by a population of perennial plants3,4, is widespread both taxonomically and geographically5, and is often associated with nutrient scarcity6. The rare production of abundant seed crops (mast events) that are orders of magnitude greater than crops during low seed years leads to high reproductive success in seed consumers and has cascading impacts in ecosystems2,7. Although it has been suggested that mast seeding is potentially synchronized at continental scales8, studies are largely constrained to local areas covering tens to hundreds of kilometres. Furthermore, summer temperature, which acts as a cue for mast seeding9, shows patterns at continental scales manifested as a juxtaposition of positive and negative anomalies that have been linked to irruptive movements of boreal seed-eating birds10,11. Here, we show a breakdown in synchrony of mast seeding patterns across space, leading to asynchrony at the continental scale. In an analysis of synchrony for a transcontinental North America tree species spanning distances of greater than 5,200 km, we found that mast seeding patterns were significantly asynchronous at distances of greater than 2,000 km apart (all P < 0.05). Other studies have shown declines in synchrony across distance, but not asynchrony. Spatiotemporal variation in summer temperatures at the continental scale drives patterns of synchrony in mast seeding, and we anticipate that this affects the spatial dynamics of numerous seed-eating communities, from insects to small mammals to the large-scale migration patterns of boreal seed-eating birds. Previous studies showing that mast seeding was synchronized at large scales were constrained to hundreds of kilometres, but this continental-scale study shows that such events are asynchronous, driving spatial and temporal impacts for a wide range of species.

Examining independent and combined accuracy of embedded performance validity tests in the California Verbal Learning Test-II and Brief Visuospatial Memory Test-Revised for detecting invalid performance.

Abstract: The California Verbal Learning Test-Second Edition (CVLT-II) Forced Choice Recognition (FC) and Brief Visuospatial Memory Test-Revised (BVMT-R) Recognition Discrimination Index (RD) are embedded performance validity tests (PVTs) assessing material-specific neuropsychological processes (i.e., verbal and visual memory, respectively). Prior research demonstrated the utility of these PVTs independently; however, no study has compared their diagnostic accuracy for identifying invalid performance relative to each other and in combination within a single sample. This cross-sectional study included an adult neuropsychiatric sample who underwent neuropsychological evaluation. Validity groups were determined via independent criterion PVT performance, and consisted of 103 participants with valid and 25 with invalid neurocognitive performance. FC and RD were not significantly correlated (r = .154), yet both differed between validity groups (ηp2 = .14-.19). Previously established FC (≤14) and RD (≤4) cutoffs evidenced 32-40% sensitivity/90-98% specificity, though receiver operating characteristic (ROC) analyses indicated a more liberal FC cutoff (≤15) was optimal. Logistic regression models utilizing both embedded PVTs indicated that FC did not significantly improve classification accuracy above and beyond RD. Results support the clinical utility of existing cutoffs for FC and RD for independently identifying invalid performance, though the latter showed relatively better ability to detect invalid performance when both are used together.

FairMatch: A Graph-based Approach for Improving Aggregate Diversity in Recommender Systems

Abstract: Recommender systems are often biased toward popular items. In other words, few items are frequently recommended while the majority of items do not get proportionate attention. That leads to low coverage of items in recommendation lists across users (i.e. low aggregate diversity) and unfair distribution of recommended items. In this paper, we introduce FairMatch, a general graph-based algorithm that works as a post-processing approach after recommendation generation for improving aggregate diversity. The algorithm iteratively finds items that are rarely recommended yet are high-quality and add them to the users' final recommendation lists. This is done by solving the maximum flow problem on the recommendation bipartite graph. While we focus on aggregate diversity and fair distribution of recommended items, the algorithm can be adapted to other recommendation scenarios using different underlying definitions of fairness. A comprehensive set of experiments on two datasets and comparison with state-of-the-art baselines show that FairMatch, while significantly improving aggregate diversity, provides comparable recommendation accuracy.

Here is something you can't understand: the suffocating whiteness of communication studies

Abstract: The authors utilize a modernity-coloniality framework to highlight practices of whiteness and white dominance within the academy and the field of communication studies in particular. The article gr...

Climate Dipoles as Continental Drivers of Plant and Animal Populations

Abstract: Ecological processes, such as migration and phenology, are strongly influenced by climate variability. Studying these processes often relies on associating observations of animals and plants with climate indices, such as the El Nino–Southern Oscillation (ENSO). A common characteristic of climate indices is the simultaneous emergence of opposite extremes of temperature and precipitation across continental scales, known as climate dipoles. The role of climate dipoles in shaping ecological and evolutionary processes has been largely overlooked. We review emerging evidence that climate dipoles can entrain species dynamics and offer a framework for identifying ecological dipoles using broad-scale biological data. Given future changes in climatic and atmospheric processes, climate and ecological dipoles are likely to shift in their intensity, distribution, and timing.

Biogeography and phylogeny of masting: do global patterns fit functional hypotheses?

Abstract: Interannual variability of seed crops (CVp) has profound consequences for plant populations and food webs, where high CVp is termed 'masting'. Here we ask: is global variation in CVp better predicted by plant or habitat differences consistent with adaptive economies of scale, in which flower and seed benefits increase disproportionately during mast years; or by passive mechanisms, in which seed production responds to variation in resource availability associated with climate variability? To address this question, we compiled a dataset for phylogenetic comparative analysis of long-term fruit/seed production for plants comprising 920 time series spanning 311 plant species. Factors associated with both adaptive benefits of CVp (wind pollination and seed dispersal) and climatic variability (variability of summer precipitation) were among the best predictors of global variation in CVp. We observed a hump-shaped relationship between CVp and latitude and intermediate phylogenetic and geographic signals in CVp. CVp is patterned nonrandomly across the globe and over the plant tree of life, where high CVp is associated with species benefiting from economies of scale of seed or flower production and with species that experience variable rainfall over summer months when seeds usually mature.

Microlearning: A New Learning Model:

Abstract: Changes in the current workplace are creating changes in traditional processes. One such process is the way that the millennial and subsequent generations joining the workplace consume learning. Th...

A Qualitative Systematic Review of Youth Participatory Action Research Implementation in U.S. High Schools.

Abstract: This qualitative systematic review examined the context-specific factors that influence the implementation of youth participatory action research (YPAR) projects in high schools within the United States. Thematic synthesis was conducted to identify and analyze the YPAR implementation factors that were present in 38 peer-reviewed studies. Results indicate the following two analytic themes concerning YPAR implementation in high schools: (a) pedagogical strategies and (b) stakeholder dynamics and needs. The themes provide support for existing ecological frameworks of implementation factors and demonstrate that adult researchers' project-specific decisions are nested within educational power structures. This paper will discuss the implications of these YPAR implementation themes in executing YPAR projects in high schools.

Climate teleconnections synchronize Picea glauca masting and fire disturbance: evidence for a fire‐related form of environmental prediction

Abstract: 1.Synchronous pulses of seed masting and natural disturbance have positive feedbacks on the reproduction of masting species in disturbance‐prone ecosystems. We test the hypotheses that disturbances and proximate causes of masting are correlated, and that their large‐scale synchrony is driven by similar climate teleconnection patterns at both inter‐annual and decadal time scales. 2.Hypotheses were tested on white spruce (Picea glauca), a masting species which surprisingly persists in fire‐prone boreal forests while lacking clear fire adaptations. We built masting, drought and fire indices at regional (Alaska, Yukon, Alberta, Quebec) and subcontinental scales (western North America) spanning the second half of the 20th century. Superposed Epoch Analysis tested the temporal associations between masting events, drought and burnt area at the regional scale. At the sub‐continental scale, Superposed Epoch Analysis tested whether El Nino‐Southern Oscillation (ENSO) and its coupled effects with the Atlantic Multidecadal Oscillation (AMO) in the positive phase (AMO+/ENSO+) synchronize drought, burnt area and masting. We additionally tested the consistency of our synchronization hypotheses on a decadal temporal scale to verify whether long‐term oscillations in AMO+/ENSO + are coherent to decadal variation in drought, burnt area and masting. 3.Analyses demonstrated synchronicity between drought, fire and masting. In all regions the year before a mast event was drier and more fire‐prone than usual. During AMO+/ENSO + events sub‐continental indices of drought and burnt area experienced significant departures from mean values. The same was observed for large‐scale masting in the subsequent year, confirming 1 year lag between fire and masting. Sub‐continental indices of burnt area and masting showed in‐phase decadal fluctuations led by the AMO+/ENSO+. Results support the “Environmental prediction hypothesis” for mast seeding. 4.Synthesis. We provide evidence of large‐scale synchronicity between seed masting in Picea glauca and fire regimes in boreal forests of western North America at both inter‐annual and decadal time scales. We conclude that seed production in white spruce predicts changes in disturbance regimes by sharing the same large‐scale climate drivers with drought and fire. This gives new insides in a mechanism providing a fire‐sensitive species with higher than expected adaptability to changes in climate.