Cliques in high-dimensional random geometric graphs

International audienceRandom geometric graphs have become now a popular object of research. Defined rather simply, these graphs describe real networks much better than classical Erdős–Rényi graphs due to their ability to produce tightly connected communities. The $n$ vertices of a random geometric graph are points in $d$-dimensional Euclidean space, and two vertices are adjacent if they are close to each other. Many properties of these graphs have been revealed in the case when $d$ is fixed. However, the case of growing dimension $d$ is practically unexplored. This regime corresponds to a real-life situation when one has a data set of n observations with a significant number of features, a quite common case in data science today. In this paper, we study the clique structure of random geometric graphs when $n \to \infty$, and $d \to \infty$, and average vertex degree grows significantly slower than $n$. We show that under these conditions, random geometric graphs do not contain cliques of size 4 a.s. if only $d >> \log^{1+\epsilon}(n)$. As for the cliques of size 3, we present new bounds on the expected number of triangles in the case $\log^2(n) << d << \log^3(n)$ that improve previously known results. In addition, we provide new numerical results showing that the underlying geometry can be detected using the number of triangles even for small $n$

Estimating the Cost of Type 1 Diabetes in the U.S.: A Propensity Score Matching Method

Diabetes costs represent a large burden to both patients and the health care system. However, few studies that examine the economic consequences of diabetes have distinguished between the two major forms, type 1 and type 2 diabetes, despite differences in underlying pathologies. Combining the two diseases implies that there is no difference between the costs of type 1 and type 2 diabetes to a patient. In this study, we examine the costs of type 1 diabetes, which is often overlooked due to the larger population of type 2 patients, and compare them to the estimated costs of diabetes reported in the literature.Using a nationally representative dataset, we estimate yearly and lifetime medical and indirect costs of type 1 diabetes by implementing a matching method to compare a patient with type 1 diabetes to a similar individual without the disease. We find that each year type 1 diabetes costs this country $14.4 billion (11.5-17.3) in medical costs and lost income. In terms of lost income, type 1 patients incur a disproportionate share of type 1 and type 2 costs. Further, if the disease were eliminated by therapeutic intervention, an estimated$10.6 billion (7.2-14.0) incurred by a new cohort and $422.9 billion (327.2-519.4) incurred by the existing number of type 1 diabetic patients over their lifetime would be avoided.We find that the costs attributed to type 1 diabetes are disproportionately higher than the number of type 1 patients compared with type 2 patients, suggesting that combining the two diseases when estimating costs is not appropriate. This study and another recent contribution provides a necessary first step in estimating the substantial costs of type 1 diabetes on the U.S

Managing aflatoxin in smallholder groundnut production in Southern Africa: Paired comparison of the windrow and Mandela cock techniques

Timely drying of groundnuts is important after harvest. In most parts of sub-Saharan Africa, moisture content reduction is practically achieved by solar drying. In particular, the groundnuts are traditionally cured in the field using the inverted windrow drying technique. Recently, the Mandela cock technique, a ventilated stack of groundnut plants with a chimney at the center, has been introduced in the southern Africa region with the aim of reducing moisture content and the risk of aflatoxin contamination. An on-farm study was conducted in Malawi to compare the effectiveness of the Mandela cock and Windrow drying techniques with respect to aflatoxin control. For two consecutive years, farmers (2016, n = 29; 2017; n = 26) were recruited to test each of the two drying techniques. A mixed-design ANOVA showed that the Mandela cock groundnut drying technique led to sig- nificantly (p < 0.001) higher aflatoxin levels in groundnut seed compared to the traditional inverted windrow drying (5.7 μg/kg, geometric mean vs 2.5 μg/kg in 2016 and 37.6 μg/kg vs 8.4 μg/kg in 2017). The present findings clearly demonstrate the need for regulation and technology validation if farmers and consumers are to benefit

Violent Governance, Identity and the Production of Legitimacy: Autodefensas in Latin America

This article examines the intersections of violence, governance, identity and legitimacy in relation to autodefensas (self-defence groups) in Latin America, focusing on Mexico and Colombia. By shifting focus from the question of where legitimacy lies to how it is produced and contested by a range of groups, we challenge the often presumed link between the state and legitimacy. We develop the idea of a field of negotiation and contestation, firstly, to discuss and critique the concept of state failure as not merely a Western hegemonic claim but also a strategic means of producing legitimacy by autodefensas. Secondly, we employ and enrich the notion of violent pluralism to discuss the pervasiveness of violence and the role of neoliberalism, and to address the question of non-violent practices of governance. We argue that the idea of a field of contestation and negotiation helps to understand the complexity of relationships that encompass the production of legitimacy and identity through (non)violent governance, whereby lines between (non)state, (non)violence, and (il)legitimacy blur and transform. Yet, we do not simply dismiss (binary) distinctions as these continue to be employed by groups in their efforts to produce, justify, challenge, contest and negotiate their own and others’ legitimacy and identity