Isogeny graphs of ordinary abelian varieties

Fix a prime number $\ell$. Graphs of isogenies of degree a power of $\ell$ are well-understood for elliptic curves, but not for higher-dimensional abelian varieties. We study the case of absolutely simple ordinary abelian varieties over a finite field. We analyse graphs of so-called $\mathfrak l$-isogenies, resolving that they are (almost) volcanoes in any dimension. Specializing to the case of principally polarizable abelian surfaces, we then exploit this structure to describe graphs of a particular class of isogenies known as $(\ell, \ell)$-isogenies: those whose kernels are maximal isotropic subgroups of the $\ell$-torsion for the Weil pairing. We use these two results to write an algorithm giving a path of computable isogenies from an arbitrary absolutely simple ordinary abelian surface towards one with maximal endomorphism ring, which has immediate consequences for the CM-method in genus 2, for computing explicit isogenies, and for the random self-reducibility of the discrete logarithm problem in genus 2 cryptography.Comment: 36 pages, 4 figure

CARMIL family proteins as multidomain regulators of actin-based motility

CARMILs are large multidomain proteins that regulate the actin-binding activity of capping protein (CP), a major capper of actin filament barbed ends in cells. CARMILs bind directly to CP and induce a conformational change that allosterically decreases but does not abolish its actin-capping activity. The CP-binding domain of CARMIL consists of the CP-interaction (CPI) and CARMIL-specific interaction (CSI) motifs, which are arranged in tandem. Many cellular functions of CARMILs require the interaction with CP; however, a more surprising result is that the cellular function of CP in cells appears to require binding to a CARMIL or another protein with a CPI motif, suggesting that CPI-motif proteins target CP and modulate its actin-capping activity. Vertebrates have three highly conserved genes and expressed isoforms of CARMIL with distinct and overlapping localizations and functions in cells. Various domains of these CARMIL isoforms interact with plasma membranes, vimentin intermediate filaments, SH3-containing class I myosins, the dual-GEF Trio, and other adaptors and signaling molecules. These biochemical properties suggest that CARMILs play a variety of membrane-associated functions related to actin assembly and signaling. CARMIL mutations and variants have been implicated in several human diseases. We focus on roles for CARMILs in signaling in addition to their function as regulators of CP and actin. </jats:p

Brokerage in commercialised healthcare systems: a conceptual framework and empirical evidence from Uttar Pradesh

In many contexts there are a range of individuals and organisations offering healthcare services that differ widely in cost, quality and outcomes. This complexity is exacerbated by processes of healthcare commercialisation. Yet reliable information on healthcare provision is often limited, and progress to and through the healthcare system may depend on knowledge drawn from prior experiences, social networks and the providers themselves. It is in these contexts that healthcare brokerage emerges and third-party actors facilitate access to healthcare. This article presents a novel framework for studying brokerage of access to healthcare, and empirical evidence on healthcare brokerage in urban slums in Lucknow, Uttar Pradesh. The framework comprises six areas of interest that have been derived from sociological and political science literature on brokerage. A framework approach was used to group observational and interview data into six framework charts (one for each area of interest) to facilitate close thematic analysis. A cadre of women in Lucknow's urban slums performed healthcare brokerage by encouraging use of particular healthcare services, organising travel, and mediating communications and fee negotiations with providers. The women emphasised their personal role in facilitating access to care and encouraged dependency on their services by withholding information from users. They received commission payments from healthcare programmes, and sometimes from users and hospitals as well, but were blamed for issues beyond their control. Disruption to their ability to facilitate low-cost healthcare meant some women lost their positions as brokers, while others adapted by leveraging old and new relationships with hospital managers. Brokerage analysis reveals how people capitalise on the complexity of healthcare systems by positioning themselves as intermediaries. Commercialised healthcare systems offer a fertile environment for such behaviours, which can undermine attainment of healthcare entitlements and exacerbate inequities in healthcare access

Does the FTC Have Blood On Its Hands? An Analysis of FTC Overreach and Abuse of Power After \u3cem\u3eLiu\u3c/em\u3e

Recent cases have called the Federal Trade Commission’s (“FTC”) enforcement methods into question. After a circuit split developed in the wake of the Seventh Circuit’s decision in Federal Trade Commission v. Credit Bureau Center, L.L.C., the Supreme Court responded by granting certiorari and consolidating the case with AMG Capital Management, L.L.C. v. Federal Trade Commission. The issue in these cases is whether Section 13(b) of the FTC Act authorizes the FTC to bypass the due process safeguards mandated by Congress in Sections 5 and 19 of the FTC Act and, in doing so, to conduct warrantless searches and seizures, unilaterally freeze assets, and impose punitive “disgorgement” monetary damages. In light of the Supreme Court’s recent decision in Securities & Exchange Commission v. Liu, it seems likely that the Court will limit the FTC’s abusive use of Section 13(b) and find in favor of the defendants in these cases. The FTC’s mission is to protect consumers from unfair or deceptive acts or practices, and for many years, one of its main enforcement methods has been disgorgement under Section 13(b) of the FTC Act. Section 13(b) gives the FTC the authority to seek preliminary and permanent injunctions when it believes that the law is being violated or is about to be violated. It does not mention disgorgement or any other restitution methods, but the FTC has spent considerable time and energy building a foundation of favorable case law to support its ability to use disgorgement. Its strategy consisted of building a body of precedent, based on old and inapplicable cases, and it has aggressively pursued this strategy with the intention of expanding its enforcement abilities. The way it has used its self-created power has caused untold damage to business owners, employees, and consumers. This Article argues that the Supreme Court should rule against the FTC in Credit Bureau Center/AMG Capital Management. The FTC used shaky and extraneous case law to expand its power to include the ability to seek disgorgement, and it has caused irreparable harm to businesses and individuals across the country. Indeed, following the FTC’s use of disgorgement as an improper remedy to seek damages, several business owners who were subjected to that improper treatment committed suicide, making the FTC a de facto judge, jury, and executioner. Part I details the methods that the FTC has used over the past few decades to expand its power to its current level. Part II argues that disgorgement is not authorized by Congress under Section 13(b). Indeed, nothing other than a preliminary or permanent injunction is authorized by Congress under Section 13(b). And Part III addresses the numerous constitutional issues that arise when a federal agency expands its power far beyond its statutory grant of power

The impacts of corporatisation of healthcare on medical practice and professionals in Maharashtra, India

A heterogeneous private sector dominates healthcare provision in many middle-income countries. In India the contemporary period has seen this sector undergo corporatisation processes characterised by emergence of large private hospitals and the takeover of medium-sized and charitable hospitals by corporate entities. Little is known about the operations of these private providers and the effects on healthcare professions as employment shifts from practitioner-owned small and medium hospitals to larger corporate settings. This article uses data from a mixed-methods study in two large cities in Maharashtra, India, to consider the implications of these contemporary changes for the medical profession. Data were collected from semi-structured interviews with 43 respondents who have detailed knowledge of healthcare in Maharashtra, and from a witness seminar on the topic of transformation in Maharashtra’s healthcare system. Transcripts from the interviews and witness seminar were analysed thematically through a combination of deductive and inductive approaches. Our findings point to a restructuring of medical practice in Maharashtra as training shifts towards private education and employment to those corporate hospitals. The latter is fuelled by substantial personal indebtedness, dwindling appeal of government employment, reduced opportunities to work in smaller private facilities, and the perceived benefits of work in larger providers. We describe a ‘re-professionalisation’ of medicine encompassing changes in employment relations, performance targets and constraints placed on professional autonomy within the private healthcare sector, that is accompanied by trends in cost inflation, medical malpractice, and distrust in doctor-patient relationships. The accompanying ‘re-stratification’ within this part of the profession affords prestige and influence to ‘star doctors’ while eroding the status and opportunity for young and early career doctors. The research raises important questions about the role that government and medical professionals’ bodies can, and should, play in contemporary transformation of private healthcare, and the implications of these trends for health systems more broadly

"Beyond aid" investments in private healthcare in developing countries

No abstract available

Particle Swarm Optimization—An Adaptation for the Control of Robotic Swarms

Particle Swarm Optimization (PSO) is a numerical optimization technique based on the motion of virtual particles within a multidimensional space. The particles explore the space in an attempt to find minima or maxima to the optimization problem. The motion of the particles is linked, and the overall behavior of the particle swarm is controlled by several parameters. PSO has been proposed as a control strategy for physical swarms of robots that are localizing a source; the robots are analogous to the virtual particles. However, previous attempts to achieve this have shown that there are inherent problems. This paper addresses these problems by introducing a modified version of PSO, as well as introducing new guidelines for parameter selection. The proposed algorithm links the parameters to the velocity and acceleration of each robot, and demonstrates obstacle avoidance. Simulation results from both MATLAB and Gazebo show close agreement and demonstrate that the proposed algorithm is capable of effective control of a robotic swarm and obstacle avoidance