Avinatan Hassidim, Deborah Marciano, Assaf Romm, and Ran I Shorrer. In Press. “The mechanism is truthful, why aren't you?.” American Economic Review: Papers and Proceedings.
The final step in getting an Israeli M.D. is performing a year-long internship in one of the hospitals in Israel. Internships are decided upon by a lottery, which is known as “The Internship Lottery”. In 2014 we redesigned the lottery, replacing it with a more efficient one. This paper presents the market, the redesign process and the new mechanism which is now in use. There are two main lessons that we have learned from this market. The first is the “Do No Harm” principle, which states that (almost) all participants should prefer the new mechanism to the old one. The second is that new approaches need to be used when dealing with two-body problems in object assignment. We focus on the second lesson, and study two-body problems in the context of the assignment problem. We show that decomposing stochastic assignment matrices to deterministic allocations is NP-hard in the presence of couples, and present a polynomial time algorithm with the optimal worst case guarantee. We also study the performance of our algorithm on real-world and on simulated data.
Erich Sackman and Avinoam Ben-Shaul. In Press. “A Short History of Membrane Physics.” In Handbook of Lipid Membranes: Molecular, Functional, and Materials Aspects. Editors: C. Safinya and J. Raedler . Taylor and Francis.
The link between Attention Deficit and Hyperactivity Disorder (ADHD) and reduced quality of life (QoL) has been well established. The current study examines the role of procrastination in explaining this link, providing a new focus for research and therapy. This study examines the involvement of procrastination in accounting for ADHD-related reduced QoL. Adult participants (N= 132) completed an online survey consisting of validated scales to assess ADHD symptoms, procrastination levels, and QoL. An indirect pathway between ADHD and quality of life through procrastination was examined. Higher levels of ADHD symptoms correlated with higher procrastination and lower quality-of-life scores. Indirect pathways between ADHD symptoms and poor QoL through levels of procrastination were identified. These results shed further light on ADHD and its association with reduced QoL and account for this link by the negative impact of procrastination on day-to-day functioning. Future research is warranted to design effective interventions for consumers with ADHD-related procrastination, targeting different aspects of quality of life.
Hormones play a decisive role in many aspects of insect biology. To study processes controlled by hormones, one needs methods to identify and quantify hormone titers and tools to enhance or suppress hormonal signaling experimentally. In this review, we focus on the key lipidic insect hormones, the juvenile hormones (JHs), and the ecdysteroids. The lipophilic nature of JH and ecdysteroids in combination with their low endogenous titers makes handling and quantification challenging but feasible owing to the improvement of analytical detection methods. Chemical and genetic approaches to modulate hormonal homeostasis have been developed based on knowledge of hormone biosynthetic and biodegrading enzymes, transporters, and receptors and enabled by advances in reverse genetics techniques. Here, we overview contemporary methods available to detect and quantify JHs and ecdysteroids from insect samples and to manipulate endocrine homeostasis.
District magnitude, or the number of seats per district, is a critical component of electoral systems. It affects key outcomes such as accountability, legislative fragmentation, and disproportionality in representation by providing different incentives for voters, candidates and representatives. Some democracies have identical-magnitude districts (e.g., single-member districts in the UK, or twenty-member districts in Macedonia) yet many elect their representatives through districts of varying magnitudes. Thus, in cross-country analyses, researchers first come up with a summary of district magnitudes per country in a single score. Although its wide range of effects is well established, the conceptualization and measurement of district magnitude and hence the production of such a score are overlooked by the comparative literature. We show that the national score of district magnitude which then serves as a key explanatory factor in a vast array of comparative cross-country studies is a thorny business, consequential for inference on the effect of district magnitude. Specifically, different conceptualizations and measurements of district magnitude lead to different scores, and those, in turn, may both mischaracterize countries and lead to different inferences. Moreover, the status quo in measurement of district magnitude—equally weighing all districts—is often misleading, and the problem is compounded by within-country variation in magnitude and malapportionment, common in Europe and Latin America, respectively. We propose two alternative measures of district magnitude—weighing districts by the share of representatives or voters in them—and provide guidance on the circumstances under which each measure should be utilized. Our analysis has implications for how this key component of electoral systems should be conceptualized, measured and employed in cross-country analyses.
Protein–protein interactions are modulated by their environment. High macromolecular solute concentrations crowd proteins and shift equilibria between protein monomers and their assemblies. We aim to understand the mechanism of crowding by elucidating the molecular-level interactions that determine dimer stability. Using 19F-NMR spectroscopy, we studied the effects of various polyethylene glycols (PEGs) on the equilibrium thermodynamics of two protein complexes: a side-by-side and a domain-swap dimer. Analysis using our mean-field crowding model shows that, contrary to classic crowding theories, PEGs destabilize both dimers through enthalpic interactions between PEG and the monomers. The enthalpic destabilization becomes more dominant with increasing PEG concentration because the reduction in PEG mesh size with concentration diminishes the stabilizing effect of excluded volume interactions. Additionally, the partially folded domain-swap monomers fold in the presence of PEG, contributing to dimer stabilization at low PEG concentrations. Our results reveal that polymers crowd protein complexes through multiple conjoined mechanisms, impacting both their stability and oligomeric state.
Social media have profoundly changed social communication practices across a vast range of contexts. To theorize these changes, numerous authors have proposed digital affordances as a conceptual lens. Yet, to date, most accounts of digital affordances either gloss broadly over crossplatform or use-dependent differences in practices; or they are highly context-specific, obstructing theoretical integration. In this article, we conceptualize social media affordances on an intermediate level of abstraction that foregrounds consequential differences in how digital social media platforms structure social communication practices. Focusing on the characteristic communication needs of social movements as an exemplary case, we identify how social media platforms present users with differential affordances for articulating public claims, building collective identities, and mobilizing contentious performances. We examine how key contextual conditions alter the value of differential affordances, potentially resulting in differential communication practices and platform preferences. We conclude by discussing key opportunities of our approach for comparative research and theory building.
