Institutional Choice and Targeted Killing: A Comparative Perspective

For over a decade, the use of targeted killing has been one of the most controversial issues in counterterrorism policy and law. One longstanding debate over this tactic concerns the allocation of decision-making and oversight authority among the branches of government. As attempts to settle this debate through textual and historical sources yield indeterminant answers, scholars tend to examine them through a functionalist prism, asking what institutional structures best serve the interests of national security while ensuring adequate accountability and preventing unnecessary force. This article, retaining that functionalist framing of that issue, will approach the question through a comparative law analysis. Three of the countries most heavily engaged in global counterterrorism—the U.S., the U.K., and Israel—have adopted substantially different approaches for regulating counterterrorism targeting, each according a primary supervisory role to a different governmental actor: the Executive in the U.S., Parliament in the U.K., and the Judiciary in Israel. This article describes, compares, and critically analyzes these approaches. Drawing on comparative institutional analysis theory, it then examines the findings and reaches three main conclusions. First, that in light of the judiciary’s unique structural perspective and expertise, some judicial involvement in developing the legal standard that guides and constrains government action is desirable. Second, that suboptimal decision-making and illegality due to executive bias are more likely to occur where the executive is accountable only to its own internal oversight mechanisms. And third, that in both presidential and parliamentarian systems, legislators do not have and are unlikely to have any sort of meaningful influence on executive behavior in this domain. The article concludes by suggesting a few possible institutional reforms

Totemic Functionalism in Foreign Affairs Law

In many Western democracies, and particularly in the United States, foreign affairs are primarily an executive enterprise. The travel ban, the exit from the Irannuclear deal, and the airstrikes against the Bashar al-Assad regime in Syria are just a few recent illustrations of unilateral assertions of presidential power. A large part of the justification for treating foreign affairs differently than other areas of public policy, in which political and judicial checks on the executive are more robust, is functional. Owing to the executive’s relative institutional advantages over the legislature and the judiciary—in expertise, knowledge, speed, unitary structure, and democratic accountability—courts afford the President considerable deference in cases relating to foreign affairs. But there is something deeply flawed in the way judges apply functionalist reasoning in this context. Instead of using functionalism for what it is—a contextual and adaptable paradigm for ascertaining whether and how much deference is desired in order to make the challenged policy or act work best—judges frequently simply rely on the executive’s special competence to apply a de facto presumption of near-total deference. I term this practice “totemic functionalism.” This Article traces the conceptual underpinnings of totemic functionalism and critically analyzes its pervasive effect in foreign affairs law. Using three case studies and other recent examples, it then shows how totemic functionalism undermines the system of checks and balances, first between the organs of government and then, indirectly, inside the executive branch. As a result, while judicial deference in foreign affairs is often excused with the assertion that other non-judicial checks provide adequate substitute, I show that the near-total deference arising from totemic functionalism insulates the President from any sort of accountability

Verifiable conditions of ℓ1\ell_1-recovery of sparse signals with sign restrictions

We propose necessary and sufficient conditions for a sensing matrix to be "s-semigood" -- to allow for exact $\ell_1$-recovery of sparse signals with at most $s$ nonzero entries under sign restrictions on part of the entries. We express the error bounds for imperfect $\ell_1$-recovery in terms of the characteristics underlying these conditions. Furthermore, we demonstrate that these characteristics, although difficult to evaluate, lead to verifiable sufficient conditions for exact sparse $\ell_1$-recovery and to efficiently computable upper bounds on those $s$ for which a given sensing matrix is $s$-semigood. We concentrate on the properties of proposed verifiable sufficient conditions of $s$-semigoodness and describe their limits of performance

Jellyfish galaxies with the IllustrisTNG simulations – No enhanced population-wide star formation according to TNG50

Due to ram-pressure stripping, jellyfish galaxies are thought to lose large amounts, if not all, of their interstellar medium. Nevertheless, some, but not all, observations suggest that jellyfish galaxies exhibit enhanced star formation compared to control samples, even in their ram pressure-stripped tails. We use the TNG50 cosmological gravity+magnetohydrodynamical simulation, with an average spatial resolution of 50-200 pc in the star-forming regions of galaxies, to quantify the star formation activity and rates (SFRs) of more than 700 jellyfish galaxies at z = 0 − 1 with stellar masses 108.3 − 10.8 M⊙ in hosts with mass 1010.5 − 14.3 M⊙. We extract their global SFRs, the SFRs within their main stellar body vs. within the tails, and we follow the evolution of the star formation along their individual evolutionary tracks. We compare the findings for jellyfish galaxies to those of diversely-constructed control samples, including against satellite and field galaxies with matched redshift, stellar mass, gas fraction and host halo mass. According to TNG50, star formation and ram-pressure stripping can indeed occur simultaneously within any given galaxy, and frequently do so. Moreover, star formation can also take place within the ram pressure-stripped tails, even though the latter is typically subdominant. However, TNG50 does not predict elevated population-wide SFRs in jellyfish compared to analogue satellite galaxies with the same stellar mass or gas fraction. Simulated jellyfish galaxies do undergo bursts of elevated star formation along their history but, at least according to TNG50, these do not translate into a population-wide enhancement at any given epoch

Jellyfish galaxies with the IllustrisTNG simulations – Citizen-science results towards large distances, low-mass hosts, and high redshifts

We present the “Cosmological Jellyfish” project - a citizen-science classification program to identify jellyfish galaxies within the IllustrisTNG cosmological simulations. Jellyfish (JF) are satellite galaxies that exhibit long trailing gas features – ‘tails’ – extending from their stellar body. Their distinctive morphology arises due to ram-pressure stripping (RPS) as they move through the background gaseous medium. Using the TNG50 and TNG100 simulations, we construct a sample of ∼80, 000 satellite galaxies spanning an unprecedented range of stellar masses, $10^{8.3-12.3}\, \mathrm{M_\odot }$, and host masses, $M_\mathrm{200,c}=10^{10.4-14.6}\, \mathrm{M_\odot }$ back to z = 2. Based on this sample, ∼90, 000 galaxy images were presented to volunteers in the citizen-science Zooniverse platform, who were asked to determine whether the galaxy image resembles a jellyfish. Based on volunteer votes, each galaxy received a score determining if it is a JF or not. This paper describes the project, the inspected satellite sample, the methodology, and the classification process that resulted in a data-set of 5,307 visually-identified jellyfish galaxies. We find that JF are common in nearly all group- and cluster-sized systems, with the JF fraction increasing with host mass and decreasing with satellite stellar mass. We highlight JF galaxies in three relatively unexplored regimes: low-mass hosts of M200, c ∼ 1011.5 − 13 M⊙, radial positions within hosts exceeding the virial radius R200, c, and at high redshift up to z = 2. The full data-set of our jellyfish scores is publicly available and can be used to select and study JF galaxies in the IllustrisTNG simulations

Retinal metric: a stimulus distance measure derived from population neural responses

The ability of the organism to distinguish between various stimuli is limited by the structure and noise in the population code of its sensory neurons. Here we infer a distance measure on the stimulus space directly from the recorded activity of 100 neurons in the salamander retina. In contrast to previously used measures of stimulus similarity, this "neural metric" tells us how distinguishable a pair of stimulus clips is to the retina, given the noise in the neural population response. We show that the retinal distance strongly deviates from Euclidean, or any static metric, yet has a simple structure: we identify the stimulus features that the neural population is jointly sensitive to, and show the SVM-like kernel function relating the stimulus and neural response spaces. We show that the non-Euclidean nature of the retinal distance has important consequences for neural decoding.Comment: 5 pages, 4 figures, to appear in Phys Rev Let

Jellyfish galaxies with the IllustrisTNG simulations – When, where, and for how long does ram pressure stripping of cold gas occur?

Jellyfish galaxies are prototypical examples of satellite galaxies undergoing strong ram pressure stripping (RPS). We analyze the evolution of 512 unique, first-infalling jellyfish galaxies from the TNG50 cosmological simulation. These have been visually inspected to be undergoing RPS sometime in the past 5 billion years (since z = 0.5), have satellite stellar masses $M_\star ^{\rm sat}\sim 10^{8-10.5}\, {\rm M}_\odot$, and live in hosts with M200c ∼ 1012 − 14.3 M⊙ at z = 0. We quantify the cold gas (T ≤ 104.5 K) removal using the tracer particles, confirming that for these jellyfish, RPS is the dominant driver of cold gas loss after infall. Half of these jellyfish are completely gas-less by z = 0, and these galaxies have earlier infall times and smaller satellite-to-host mass ratios than their gaseous counterparts. RPS can act on jellyfish galaxies over long time scales of ≈1.5 − 8 Gyr. Jellyfish in more massive hosts are impacted by RPS for a shorter time span and, at a fixed host mass, jellyfish with less cold gas at infall and lower stellar masses at z = 0 have shorter RPS time spans. While RPS may act for long periods of time, the peak RPS period – where at least 50 per cent of the total RPS occurs – begins within ≈1 Gyr of infall and lasts ≲ 2 Gyr. During this period, the jellyfish are at host-centric distances ∼0.2 − 2R200c, illustrating that much of RPS occurs at large distances from the host galaxy. Interestingly, jellyfish continue forming stars until they have lost ≈98 per cent of their cold gas. For groups and clusters in TNG50 $(M_{\rm 200c}^{\rm host}\sim 10^{13-14.3}\, {\rm M}_\odot )$, jellyfish galaxies deposit more cold gas (∼1011 − 12 M⊙) into halos than exist in them at z = 0, demonstrating that jellyfish, and in general satellite galaxies, are a significant source of cold gas accretion