We study the identification of individual-level associations when only aggregate data are available. We characterize the biases of, and relationships among, canonical ecological inference (EI) estimators. We use these results to develop a partial identification approach: monotone EI. The approach exploits information about one or both of the following conditional associations: (1) outcome differences between groups within the same neighborhood and (2) outcome differences within the same group between neighborhoods with different group compositions. We show how assumptions about the sign of these conditional associations, whether individually or in relation to one another, can yield informative sharp bounds. We illustrate our results using county-level data to study differences in COVID-19 vaccination rates among Republicans and Democrats in the United States.

In this work, the life cycle of Gnathostoma turgidum was studied both in natural temporary water bodies and under experimental conditions, with materials collected from the municipality of San Francisco Ixhuatán, Oaxaca. Adult nematodes inhabit the interstitial layers of the stomach in the definitive host (Didelphis virginiana) and release their eggs into the environment via faeces, typically in a dry environment. Under these conditions, the eggs remain quiescent until the onset of the rainy season. Development of early third-stage larvae occurs in cyclopoid copepods. Fry acts as transport and/or intermediate hosts, while frogs (Lithobates forreri) serve as obligatory intermediate hosts for advanced third-stage larvae, ultimately transmitting the parasites to the definitive host. Notably, the precocity phenomenon, typical of larval development in intermediate hosts, occurs in this species within the definitive host. Precocity is likely a response to host behaviour or other ecological factors that restrict transmission to narrow spatial and temporal windows. Adults die at the end of the rainy season. The marked seasonality of this species is mainly attributed to the combination of two factors: (i) the seasonal predation of frogs by the definitive host, and (ii) expulsion of adult stages as immune-mediated ‘self-cure’. This study represents the first documentation of birds acting as paratenic hosts for this nematode.

A massive amount of research examines the representation of public opinion by policymakers, increasingly on actual policy actions. The work often provides evidence of a positive association between expressed public preferences and policy, but only some of the time and only to some degree, and there is even less evidence of responsiveness. This essay delves into the conditions for responsiveness, focusing on public demand for policy and policy supply, building on what research on the subjects reveals. The examination makes clear that policy responsiveness requires a great deal of both the represented and the representatives (and scholars too) and that these conditions are not easily met, though sometimes are. The emergent structure seemingly is much as empirical democratic theory would predict, and helps account for patterns of policy “responsiveness” we observe. The concluding section contemplates future research.

Physics-informed neural networks (PINNs) are a promising alternative for extracting additional time-averaged (mean) flow quantities from experimental data. In the case of particle image velocimetry (PIV), for example, the measured mean flow field is contaminated by noise, has a limited field of view, is restricted to a uniform grid, and does not provide the pressure field. To overcome these limitations, we present a methodology in which PINNs are first trained on a Reynolds-averaged Navier–Stokes (RANS) simulation such that it learns all states at every location in the domain. We then apply transfer learning, which updates the PINN using sub-sampled PIV data. The resulting predictions are in significantly better agreement with the full PIV dataset than PINNs, which are trained on experimental data only. This work builds on the recent literature by integrating a Spalart-Allmaras turbulence model and applying hard constraints to the no-slip wall boundary condition. We apply this methodology to a two-dimensional NACA 0012 airfoil inclined at an angle of attack, $ \alpha $ = 15°, for two Reynolds numbers of Re = 10,000 and 75,000. The proposed methodology is initially validated using large eddy simulation (LES) data and then demonstrated on experimental PIV data. Our transfer learning approach results in improved predictions and a reduction in training time when compared to using a random network initialization.

Let $\{Y_{n}$, $n \geq 1\}$ be a critical branching process with immigration having finite variance for the offspring number of particles and finite mean for the immigrating number of particles. In this paper we study lower deviation probabilities for $Y_{n}$. More precisely, assuming that $k,n \to \infty$ so that $k={\mathrm{o}} (n)$, we investigate the asymptotics of $\mathbb P(Y_{n} \leq k )$ and $\mathbb P(Y_{n} = k )$. Our results clarify the role of the moment conditions in the local limit theorem for $Y_n$ proved by Mellein (1982).

Let G be a connected Lie group and $\mathrm {Sub}_G$ be the space of closed subgroups of G equipped with the Chabauty topology. In this article, we investigate the existence of invariant random subgroups of G supported on various orbits of the conjugation action of G on $\mathrm {Sub}_G$.

Wlezien offers a compelling framework of policy “inputs” and “outputs” to better understand policy responsiveness. Building on this framework, I argue that inequality in policy influence is central to understanding policy responsiveness and must be treated as a first-order concern: disparities in political power complicate both sides of the “inputs” and “outputs” equation. Disadvantaged groups face barriers in signaling preferences and shaping policy agendas, while policymakers respond unequally across groups. These inequalities challenge how we measure responsiveness and question whether aggregate measures capture democratic quality when preferences are polarized along entrenched social cleavages. Institutional reforms designed to improve representation – from public comment periods to the Voting Rights Act – may serve their stated goals while simultaneously producing unintended consequences for equitable responsiveness. I contend that scholars must ask not just whether policy responds to public opinion, but whose opinion it follows. Responsiveness may be necessary but insufficient for democratic legitimacy if one does not reckon with unequal political power.

In “On Policy Responsiveness,” Wlezien provides a realist account of policy responsiveness. While recognizing it as a democratic good, he identifies the many obstacles that must be overcome and conditions that must be met to achieve it. Wlezien suggests that “it may be surprising that we observe any representation at all,” considering the many conditions that must be met to achieve it. This raises an important and challenging question, which we expand upon here: what is an appropriate level of responsiveness to expect from democratic systems and what level of observed policy congruence might we deem surprising and/or sufficient? The question of an appropriate counterfactual, apart from being crucial to guide research and hypothesis testing, also creates this fruitful opportunity for collaboration and discussion between a normative political theorist (Scudder) and an empirical political scientist (Grillos). Here, we identify two sources of counterfactual thinking, one normative and one empirical, to provide a benchmark against which we can judge observed levels of policy responsiveness.

Quantitative studies of policy responsiveness are liable to overstate the fairness and quality of democratic governance, because they neglect to account for forms of capture and distortion by powerful groups that are more difficult to operationalize and measure. The field essay by Christopher Wlezien that surveys these studies is comprehensive and generally fair, but it nevertheless shares the blind spots of that literature as a whole, and therefore dismisses realist skepticism (such as that of Achen and Bartels) too quickly. By properly situating this literature within broader discussions of democratic values and political equality, this response aims to recenter the big picture – and highlight what may be concealed when we give too much weight to policy responsiveness.