Is there a rural penalty in language acquisition? Evidence from Germany’s refugee allocation policy

Emerging evidence has highlighted the important role of local contexts on integration trajectories of asylum seekers and refugees. Germany’s policy of randomly allocating asylum seekers across Germany may advantage some and disadvantage others in terms of opportunities for equal participation in society. This study explores the question whether asylum seekers that have been allocated to rural areas experience disadvantages in terms of language acquisition compared to those allocated to urban areas. We derive testable assumptions using a Directed Acyclic Graph (DAG) which are then tested using large-N survey data (IAB-BAMF-SOEP refugee survey). We find that living in a rural area has no negative total effect on language skills. Further the findings suggest that the ‘null effect’ is the result of two processes which offset each other: while asylum seekers in rural areas have slightly lower access for formal, federally organized language courses, they have more regular exposure to German speakers.

Hole probability for non-interacting fermions in a d-dimensional trap

The hole probability, i.e., the probability that a region is void of particles, is a benchmark of correlations in many body systems. We compute analytically this probability P (R) for a sphere of radius R in the case of N noninteracting fermions in their ground state in a d-dimensional trapping potential. Using a connection to the Laguerre-Wishart ensembles of random matrices, we show that, for large N and in the bulk of the Fermi gas, P (R) is described by a universal scaling function of kF R, for which we obtain an exact formula (kF being the local Fermi wave-vector). It exhibits a super exponential tail P (R) / e-κd(kF R)d+1 where κdis a universal amplitude, in good agreement with existing numerical simulations. When R is of the order of the radius of the Fermi gas, the hole probability is described by a large deviation form which is not universal and which we compute exactly for the harmonic potential. Similar results also hold in momentum space.

A qualitative assessment of QCA: method stretching in large-N studies and temporality

Qualitative Comparative Analysis (QCA) is a descriptive research method that can provide causal explanations for an outcome of interest. Despite extensive quantitative assessments of the method, my objective is to contribute to the scholarly discussion with insights constructed through a qualitative lens. Researchers using the QCA approach have less ability to incorporate and nuance information on set membership as the number of cases grows. While recognizing the suggested ways to overcome such challenges, I argue that since setting criteria for membership, calibrating, and categorizing are crucial QCA aspects that require in-depth knowledge, QCA is unfit for larger-N studies. Additionally, I also discuss that while the method is able to identify various parts of a causal configuration—the ‘what’—it falls short to shed light on the ‘how’ and ‘why,’ especially when temporality matters. Researchers can complement it with other methods, such as process tracing and case studies, to fill in these missing explanatory pieces or clarify contradictions—which begs the question of why they would also choose to use QCA.

Curiosity might not help after all: Predicted trajectories for need for cognition and anxiety and depression symptoms based on findings by Zainal and Newman (2022)

In a recent article, Zainal and Newman (2022) reported that need for cognition (NFC) predicted anxiety and depression symptoms (ADS) across 10 years in a large (N = 6750) sample of community-dwelling adults, and furthermore that a within-person decrease in NFC was associated with an increase in ADS. Here, we analyze the modeling approaches used in that paper, and show that the two different modeling strategies employed give contradictory results, suggesting that the results are influenced by statistical artifacts and should be interpreted with caution.

Does Empathy Promote Helping by Activating Altruistic Motivation or Concern About Social Evaluation? A Direct Replication of Fultz et al. (1986)

Empathy motivates people to help needy others. Does it do so by activating genuine concern, or by activating more self-interested goals that helping needy others might enable them to fulfill? The empathy-altruism hypothesis claims that empathic concern reflects a non-instrumental desire to improve the welfare of a person in need. To rule out the alternative hypothesis that empathy motivates prosocial behavior by first generating fear of appearing selfish, Fultz et al. (1986) manipulated empathy for a needy target using perspective-taking instructions; they also manipulated whether the subject’s opportunity to help was subject to social evaluation. However, Fultz et al.’s (1986) experiments were underpowered. Here, we conducted a large-N pre-registered replication of Experiment 2 in Fultz et al. (1986). We also administered self-report measures of moral identity and endorsement of the principle of care to test whether these traits reflect altruistic desires or desires to avoid disapprobation. We found that volunteering did not differ between the high and low social evaluation conditions, and that volunteering was not significantly higher in the high-empathy condition. These results sit uneasily with Fultz et al. (1986)’s evidence in support of the empathy-altruism hypothesis. We also failed to find evidence that the principle of care or moral identity internalization reflect altruistic motivation. Consistent with the empathy-altruism hypothesis, however, we did find that self-reported empathic concern predicted helping.

Servants of two (or more) masters: Accounting for the complexity of intraparty candidate selection methods

Intraparty candidate selection methods are the drivers of many topics of interest to political scientists. Their operationalization, however, is made complicated because they tend to involve multiple selectorates that differ in their levels of inclusiveness and centralization and that play various roles within the process. This complexity poses a challenge for large- n comparative studies. Drawing on the Political Parties DataBase Round Two to analyze candidate selection methods in 184 parties from 35 democracies, we highlight the inadequacy of the currently available measures to correctly account for this complexity in large- n studies and offer improvements on this front. Specifically, we propose a continuous measure of inclusiveness that better captures the complexity of candidate selection methods and a new measure of complexity to facilitate future analyses into this feature. We recommend that scholars in other cross-national projects consider adopting similar or improved coding strategies in order to better capture these complexities.

A perturbative CFT dual for pure NS-NS AdS3 strings

We construct a conformal field theory dual to string theory on AdS3 with pure NS-NS flux. It is given by a symmetric orbifold of a linear dilaton theory deformed by a marginal operator from the twist-2 sector. We compute two- and three-point functions on the CFT side to 4th order in conformal perturbation theory at large N. They agree with the string computation at genus 0, thus providing ample evidence for a duality. We also show that the full spectra of both short and long strings on the CFT and the string side match. The duality should be understood as perturbative in 1/N.

Unstructured search by random and quantum walk

The task of finding an entry in an unsorted list of $N$ elements famously takes $O(N)$ queries to an oracle for a classical computer and $O(\sqrt{N})$ queries for a quantum computer using Grover's algorithm. Reformulated as a spatial search problem, this corresponds to searching the complete graph, or all-to-all network, for a marked vertex by querying an oracle. In this tutorial, we derive how discrete- and continuous-time (classical) random walks and quantum walks solve this problem in a thorough and pedagogical manner, providing an accessible introduction to how random and quantum walks can be used to search spatial regions. Some of the results are already known, but many are new. For large $N$, the random walks converge to the same evolution, both taking $N \ln(1/\epsilon)$ time to reach a success probability of $1-\epsilon$. In contrast, the discrete-time quantum walk asymptotically takes $\pi\sqrt{N}/2\sqrt{2}$ timesteps to reach a success probability of $1/2$, while the continuous-time quantum walk takes $\pi\sqrt{N}/2$ time to reach a success probability of $1$.

Large N external-field quantum electrodynamics

We advocate the study of external-field quantum electrodynamics with N charged particle flavors. Our main focus is on the Heisenberg-Euler effective action for this theory in the large N limit which receives contributions from all loop orders. The contributions beyond one loop stem from one-particle reducible diagrams. We show that specifically in constant electromagnetic fields the latter are generated by the one-loop Heisenberg-Euler effective Lagrangian. Hence, in this case the large N Heisenberg-Euler effective action can be determined explicitly at any desired loop order. We demonstrate that further analytical insights are possible for electric-and magnetic-like field configurations characterized by the vanishing of one of the secular invariants of the electromagnetic field and work out the all-orders strong field limit of the theory.