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In this work, we revisit and elaborate on twisted holography for AdS$_3 × S^3 × X$ with $X= T^4$, K3, with a particular focus on K3. We describe the twist of supergravity, identify the corresponding (generalization of) BCOV theory, and enumerate twisted supergravity states. We use this knowledge, and the technique of Koszul duality, to obtain the $N → ∞$, or planar, limit of the chiral algebra of the dual CFT. The resulting symmetries are strong enough to fix planar 2 and 3-point functions in the twisted theory or, equivalently, in a 1/4-BPS subsector of the original duality. This technique can in principle be used to compute corrections to the chiral algebra perturbatively in $1/N$.

BackgroundWhile strong evidence supports adverse maternal and offspring consequences of air pollution, mechanisms that involve the placenta, a key part of the intrauterine environment, are largely unknown. Previous studies of air pollution and placental gene expression were small candidate gene studies that rarely considered prenatal windows of exposure or the potential role of offspring sex. We examined overall and sex-specific associations of prenatal exposure to fine particulate matter (PM2.5) with genome-wide placental gene expression.MethodsParticipants with placenta samples, collected at birth, and childhood health outcomes from CANDLE (Memphis, TN) (n = 776) and GAPPS (Seattle, WA) (n = 205) cohorts of the ECHO-PATHWAYS Consortium were included in this study. PM2.5 exposures during trimesters 1, 2, 3, and the first and last months of pregnancy, were estimated using a spatiotemporal model. Cohort-specific linear adjusted models were fit for each exposure window and expression of >11,000 protein coding genes from paired end RNA sequencing data. Models with interaction terms were used to examine PM2.5-offspring sex interactions. False discovery rate (FDR

Title IX prohibits sex-discrimination in colleges in the United States. While colleges must provide training on Title IX, little is known about its effectiveness. This study examined the campus climate and effectiveness of Title IX training among 2,393 college students at a medium-size public university in the south-central region of the U.S. Results indicated 68% of students reported they understood Title IX, yet only 14% correctly understood Title IX prohibited sex-discrimination and 16% correctly understood reporting procedures. Regression analyses found few significant effects for demographics, academic characteristics, satisfaction with the campus, and beliefs about university support on training participation, training knowledge, and help seeking for sexual assault survivors. Positive perceptions of campus climate increased participation in training, efficacy of training, and confidence in helping sexual assault survivors. However, participation in training was negatively impacted by perceptions of faculty support. Age, asexual identity, and Asian identity affected training participation and efficacy.

The present study explored the impacts of a contextualised outdoor science curriculum on "what" and "how" elementary students learn when immersed in the local contexts in which natural phenomena occur. We conducted 63 individual interviews with fifth- and sixth-graders (between 10 and 12 years old) living in the inner city of Montréal, Québec province, Canada. These allowed us to identify: (1) three categories of impacts on "what" students learned: "evolution of conceptual understanding about living organisms, development of scientific investigation abilities," and "evolution of connection to nature;" and (2) two categories of impacts on "how" students learned: "a context that encourages deeper learning" and "a context that promotes engagement." Our results show that impacts on students went beyond learning about living organisms. A strength of our findings is that although the method of data collection did not aim a priori to corroborate the work of other research in the field of outdoor education, it in fact corroborated several results from other research, which is an important step for the development of this field. We also found that some students developed a connection to nature without addressing environmental problems during outdoor activities.

The growing use of machine learning for the data-driven study of social issues and the implementation of data-driven decision processes has required researchers to re-examine the often implicit assumption that datadriven models are neutral and free of biases. The careful examination of machine-learned models has identified examples of how existing biases can inadvertently be perpetuated in fields such as criminal justice, where failing to account for racial prejudices in the prediction of recidivism can perpetuate or exasperate them, and natural language processing, where algorithms trained on human languages corpora have been shown to reproduce strong biases in gendered descriptions. These examples highlight the importance of thinking about how biases might impact the study of educational data and how data-driven models used in educational contexts may perpetuate inequalities. To understand this question, we ask whether and how demographic information, including age, educational level, gender, race/ethnicity, socioeconomic status (SES), and geographical location, is used in Educational Data Mining (EDM) research. Specifically, we conduct a systematic survey of the last five years of EDM publications that investigates whether and how demographic information about the students is reported in EDM research and how this information is used to 1) "investigate" issues related to demographics, 2) use the information as "input features for data-driven analyses," or 3) to "test and validate models." This survey shows that, although a majority of publications reported at least one category of demographic information, the frequency of reporting for different categories of demographic information is very uneven (ranging from 5% to 59%), and only 15% of publications used demographic information in their analyses.

Average-case analysis computes the complexity of an algorithm averaged over all possible inputs. Compared to worst-case analysis, it is more representative of the typical behavior of an algorithm, but remains largely unexplored in optimization. One difficulty is that the analysis can depend on the probability distribution of the inputs to the model. However, we show that this is not the case for a class of large-scale problems trained with first-order methods including random least squares and one-hidden layer neural networks with random weights. In fact, the halting time exhibits a universality property: it is independent of the probability distribution. With this barrier for average-case analysis removed, we provide the first explicit average-case convergence rates showing a tighter complexity not captured by traditional worst-case analysis. Finally, numerical simulations suggest this universality property holds for a more general class of algorithms and problems., Author(s): Courtney Paquette [sup.1] [sup.2], Bart van Merriënboer [sup.2], Elliot Paquette [sup.1], Fabian Pedregosa [sup.2] Author Affiliations: (1) grid.14709.3b, 0000 0004 1936 8649, Department of Mathematics and Statistics, McGill University, [...]

IntroductionMounting evidence suggests that geographic ranges of tree species worldwide are shifting under global environmental changes. Little is known, however, about if and how these species’ range shifts may trigger the range shifts of various types of forests. Markowitz’s portfolio theory of investment and its broad application in ecology suggest that the range shift of a forest type could differ substantially from the range shifts of its constituent tree species.MethodsHere, we tested this hypothesis by comparing the range shifts of forest types and the mean of their constituent species between 1970–1999 and 2000–2019 across Alaska, Canada, and the contiguous United States using continent-wide forest inventory data. We first identified forest types in each period using autoencoder neural networks and K-means cluster analysis. For each of the 43 forest types that were identified in both periods, we systematically compared historical range shifts of the forest type and the mean of its constituent tree species based on the geographic centroids of interpolated distribution maps.ResultsWe found that forest types shifted at 86.5 km·decade-1 on average, more than three times as fast as the average of constituent tree species (28.8 km·decade-1). We showed that a predominantly positive covariance of the species range and the change of species relative abundance triggers this marked difference.DiscussionOur findings provide an important scientific basis for adaptive forest management and conservation, which primarily depend on individual species assessment, in mitigating the impacts of rapid forest transformation under climate change.

Background: Surgery for degenerative spine pathologies is typically performed on a scheduled basis; however, worsening symptoms may warrant emergency surgery. An increasing number of patients requiring emergency surgery has been observed (22.6% in 2006 to 34.8% in 2019). We sought to compare the outcomes of patients who received scheduled surgery and those who required emergency surgery. Methods: All patients treated between Jan. 1, 2006, and Dec. 31, 2019, were included. Retrospective comparisons were made between patients who were scheduled (elective) for surgery and those requiring emergency surgery, patients who were scheduled for surgery and those who decompensated while on the surgical waitlist and patients who presented as de novo emergencies and those who decompensated while on the surgical waitlist. Results: Among the 6217 patients with degenerative pathologies, 4654 (74.9%) patients were scheduled (elective) for surgery and 1563 (25.1%) were patients requiring emergency surgery. Compared with patients who were scheduled, patients requiring emergency surgery had a longer length of stay (LOS) in hospital (5.1 d, interquartile range [IQR] 2.7-11.2 v. 3.6 d, IQR 1.3-6.4, p < 0.001) and lower rate of home discharge (78.6% v. 94.2%, p < 0.001). Patients requiring emergency surgery were 1.34 times more likely to have any adverse events (95% confidence interval [CI] 1.06-1.68, p = 0.01). When compared with patients who were scheduled for surgery, those who decompensated while on the surgical waitlist had longer LOS (7.0 d, IQR 3.3-15.0 v. 3.6 d, IQR 1.3-6.4, p < 0.001), less home discharge (77.6% v. 94.2%, p < 0.001) and were 2.5 times more likely to have any adverse events (95% CI 1.5-4.1, p < 0.001). Patients who decompensated had a 2.1 times higher risk of having any adverse events than patients who presented as de novo emergencies (95% CI 1.2-3.6, p< 0.001). Conclusion: We observed worse perioperative outcomes for patients requiring emergency surgery for degenerative spinal conditions than for patients who were scheduled for surgery. Patients who decompensated while on the surgical waitlist had the worst outcomes. Contexte: Le traitement chirurgical des pathologies dégénératives de la colonne vertébrale est généralement planifié; l'aggravation des symptômes peut toutefois justifier une opération d'urgence. On constate d'ailleurs qu'un pourcentage croissant de patients ont besoin d'une telle intervention (22,6% en 2006 comparativement à 34,8% en 2019). Nous avons cherché à comparer les issues des patients ayant subi une intervention planifiée avec celles des patients nécessitant une opération d'urgence. Méthodes: Tous les patients traités entre le 1er janvier 2006 et le 31 décembre 2019 ont été inclus. Nous avons établi des comparaisons rétrospectives entre les patients allant subir une intervention planifiée (non urgente) et ceux ayant besoin d'une opération d'urgence, entre les patients allant subir une intervention planifiée et ceux ayant subi une décompensation alors qu'ils étaient sur une liste d'attente, et entre les patients nécessitant une opération urgente pour une pathologie de novo et ceux ayant subi une décompensation alors qu'ils étaient sur une liste d'attente. Résultats: Parmi les 6217 patients présentant des pathologies dégénératives, 4654 (74,9%) allaient subir une intervention planifiée (non urgente) et 1563 (25,1%) avaient besoin d'une opération d'urgence. Comparativement aux premiers, ces derniers restaient plus longtemps à l'hôpital (5,1 jours [écart interquartile (EI) 2,7-11,2] c. 3,6 jours [EI 1,3-6,4], p < 0,001) et présentaient un taux de congé plus faible (78,6% c. 94,2%, p < 0,001). Ils étaient 1,34 fois plus susceptibles d'être victimes d'un événement indésirable (intervalle de confiance [IC] de 95% 1,06-1,68, p = 0,01). Comparativement aux patients pour lesquels une intervention était prévue, ceux ayant subi une décompensation alors qu'ils étaient sur une liste d'attente restaient plus longtemps à l'hôpital (7,0 jours [EI 3,3-15,0] c. 3,6 jours [EI 1,3-6,4], p < 0,001), présentaient un taux de congé plus faible (77,6% c. 94,2%, p < 0,001) et étaient 2,5 fois plus susceptibles de subir un événement indésirable (IC de 95% 1,5-4,1, p < 0,001). Les patients ayant subi une décompensation présentaient un risque 2,1 fois plus élevé d'être victimes d'un événement indésirable, comparativement aux patients nécessitant une opération urgente pour une pathologie de novo (IC de 95% 1,2-3,6, p < 0,001). Conclusion: Nous avons observé des issues périopératoires moins favorables chez les patients ayant besoin de se faire opérer d'urgence pour des pathologies dégénératives de la colonne vertébrale, comparativement à ceux pour lesquels une intervention était prévue. Les patients ayant subi une décompensation alors qu'ils étaient sur une liste d'attente présentaient les pires issues., Older age demographics have increased the demand for spinal surgery, creating an ever-increasing burden for the health care system. (1) This is especially true for degenerative spinal pathologies such as [...]

Abstract Bacterial conjugation is a major horizontal gene transfer mechanism. While the functions encoded by many conjugative plasmids have been intensively studied, the contribution of recipient chromosome-encoded genes remains largely unknown. Here, we analyzed the genetic requirement of recipient cells for conjugation of IncI2 plasmid TP114, which was recently shown to transfer at high rates in the gut microbiota. We performed transfer assays with ~4,000 single-gene deletion mutants of Escherichia coli. When conjugation occurs on a solid medium, we observed that recipient genes impairing transfer rates were not associated with a specific cellular function. Conversely, transfer assays performed in broth were largely dependent on the lipopolysaccharide biosynthesis pathway. We further identified specific structures in lipopolysaccharides used as recipient cell surface receptors by PilV adhesins associated with the type IVb accessory pilus of TP114. Our strategy is applicable to study other mobile genetic elements and understand important host cell factors for their dissemination.

Abstract We elaborate on various aspects of our top-down celestial holographic duality wherein the semiclassical bulk spacetime is a 4d asymptotically flat, self-dual Kähler geometry known as Burns space. The bulk theory includes an open string sector comprising a 4d WZW model and a closed string sector called “Mabuchi gravity” capturing fluctuations of the Kähler potential. Starting with the type I topological B-model on the twistor space of flat space, we obtain the twistor space of Burns space from the backreaction of a stack of N coincident D1 branes, while the chiral algebra is obtained from (a twist of) the brane worldvolume theory. One striking consequence of this duality is that all loop-level scattering amplitudes of the theory on Burns space can be expressed as correlation functions of an explicit 2d chiral algebra. We also present additional large-N checks, matching several 2 and 3-point amplitudes and their collinear expansions in the WZW4 sector, and the mixed WZW4-Mabuchi sector, of the bulk theory to the corresponding 2 and 3-point vacuum correlators and operator product expansions in the dual chiral algebra. Key features of the duality, along with our main results, are summarized in the introduction.