Antithetic and Monte Carlo kernel estimators for partial rankings

In the modern age, rankings data is ubiquitous and it is useful for a variety of applications such as recommender systems, multi-object tracking and preference learning. However, most rankings data encountered in the real world is incomplete, which prevents the direct application of existing modelling tools for complete rankings. Our contribution is a novel way to extend kernel methods for complete rankings to partial rankings, via consistent Monte Carlo estimators for Gram matrices: matrices of kernel values between pairs of observations. We also present a novel variance reduction scheme based on an antithetic variate construction between permutations to obtain an improved estimator for the Mallows kernel. The corresponding antithetic kernel estimator has lower variance and we demonstrate empirically that it has a better performance in a variety of Machine Learning tasks. Both kernel estimators are based on extending kernel mean embeddings to the embedding of a set of full rankings consistent with an observed partial ranking. They form a computationally tractable alternative to previous approaches for partial rankings data. An overview of the existing kernels and metrics for permutations is also provided

Exploring how people with chronic pain understand their pain: A qualitative study

A fundamental principle of pain management is educating patients on their pain using current neuroscience. However, current pain neurophysiology education (PNE) interventions show variable success in improving pain outcomes, and may be difficult to integrate with existing understanding of pain. This study aimed to investigate how people with chronic pain understand their pain, using qualitative exploration of their conceptualisations of pain, and how this understanding accommodated, or resisted, the messages of PNE. Twelve UK adults with chronic pain were recruited through advertisements on online pain networks. Semi-structured interviews were conducted remotely, with responses elicited using the Grid Elaboration Method (GEM) and then a PNE article. Participants' grid elaborations and responses to PNE were analysed using thematic analysis (TA). Three main themes were extracted from participants' grid elaborations: communicating pain, explaining pain and living with pain. These themes incorporated varied, inconsistent sub-themes: of pain as simultaneously experiential and conceptual; in the body and in the mind; diagnosable and inexplicable; manageable and insuperable. Generalised, meta-level agreement was identified in participants' PNE responses, but with doubts about its practical value. This study shows that people understand pain through inconsistent experiential models that may resist attempts at conceptual integration. Participants' elaborations showed diverse and dissonant conceptualisations, with experiential themes of restricted living; assault on the self; pursuit of understanding pain and abandonment of that pursuit. Responses, although unexpectedly compatible with PNE, suggested that PNE was perceived as intellectually engaging but practically inadequate. Experiential disconfirmation may be required for behavioural change inhibited by embedded fears and aversive experiences. UCL REC# 17833/003

Canonical Melnikov theory for diffeomorphisms

We study perturbations of diffeomorphisms that have a saddle connection between a pair of normally hyperbolic invariant manifolds. We develop a first-order deformation calculus for invariant manifolds and show that a generalized Melnikov function or Melnikov displacement can be written in a canonical way. This function is defined to be a section of the normal bundle of the saddle connection. We show how our definition reproduces the classical methods of Poincar\'{e} and Melnikov and specializes to methods previously used for exact symplectic and volume-preserving maps. We use the method to detect the transverse intersection of stable and unstable manifolds and relate this intersection to the set of zeros of the Melnikov displacement.Comment: laTeX, 31 pages, 3 figure

Dominant B-cell epitopes from cancer/stem cell antigen SOC2 recognized by serum samples from cancer patients

Cataloged from PDF version of article.Human sex determining region Y-box 2 (SOX2) is an important transcriptional factor involved in the pluripotency and stemness of human embryonic stem cells. SOX2 plays important roles in maintaining cancer stem cell activities of melanoma and cancers of the brain, prostate, breast, and lung. SOX2 is also a lineage survival oncogene for squamous cell carcinoma of the lung and esophagus. Spontaneous cellular and humoral immune responses against SOX2 present in cancer patients classify it as a tumor-associated antigen (TAA) shared by lung cancer, glioblastoma, and prostate cancer among others. In this study, B-cell epitopes were predicted using computer-assisted algorithms. Synthetic peptides based on the prediction were screened for recognition by serum samples from cancer patients using ELISA. Two dominant B-cell epitopes, SOX2:52-87 and SOX2:98-124 were identified. Prostate cancer, glioblastoma and lung cancer serum samples that recognized the above SOX2 epitopes also recognized the full-length protein based on Western blot. These B-cell epitopes may be used in assessing humoral immune responses against SOX2 in cancer immunotherapy and stem cell-related transplantation

Measurement Challenges for Cyber Cyber Digital Twins: Experiences from the Deployment of Facebook's WW Simulation System

A cyber cyber digital twin is a deployed software model that executes in tandem with the system it simulates, contributing to, and drawing from, the systems behaviour. This paper outlines Facebooks cyber cyber digital twin, dubbed WW, a twin of Facebooks WWW platform, built using web-enabled simulation. The paper focuses on the current research challenges and opportunities in the area of measurement. Measurement challenges lie at the heart of modern simulation. They directly impact how we use simulation outcomes for automated online and semi-Automated offline decision making. Measurements also encompas how we verify and validate those outcomes. Modern simulation systems are increasingly becoming more like cyber cyber digital twins, effectively moving from manual to automated decision making, hence, these measurement challenges acquire ever greater significance

Testing web enabled simulation at scale using metamorphic testing

We report on Facebook's deployment of MIA (Metamorphic Interaction Automaton). MIA is used to test Facebook's Web Enabled Simulation, built on a web infrastructure of hundreds of millions of lines of code. MIA tackles the twin problems of test flakiness and the unknowable oracle problem. It uses metamorphic testing to automate continuous integration and regression test execution. MIA also plays the role of a test bot, automatically commenting on all relevant changes submitted for code review. It currently uses a suite of over 40 metamorphic test cases. Even at this extreme scale, a non-trivial metamorphic test suite subset yields outcomes within 20 minutes (sufficient for continuous integration and review processes). Furthermore, our offline mode simulation reduces test flakiness from approximately 50% (of all online tests) to 0% (offline). Metamorphic testing has been widely-studied for 22 years. This paper is the first reported deployment into an industrial continuous integration system

Facebook’s Cyber–Cyber and Cyber–Physical Digital Twins

A cyber-cyber digital twin is a simulation of a software system. By contrast, a cyber-physical digital twin is a simulation of a non-software (physical) system. Although cyber-physical digital twins have received a lot of recent attention, their cyber-cyber counterparts have been comparatively overlooked. In this paper we show how the unique properties of cyber-cyber digital twins open up exciting opportunities for research and development. Like all digital twins, the cyber-cyber digital twin is both informed by and informs the behaviour of the twin it simulates. It is therefore a software system that simulates another software system, making it conceptually truly a twin, blurring the distinction between the simulated and the simulator. Cyber-cyber digital twins can be twins of other cyber-cyber digital twins, leading to a hierarchy of twins. As we shall see, these apparently philosophical observations have practical ramifications for the design, implementation and deployment of digital twins at Facebook

Enemigos naturales de Dactylopius Opuntiae (Cockerell) en opuntia ficus-indica (l.) Miller en el centro de México

. Prickly pear, Opuntia ficus-indica (L.) Miller, is cultivated for many purposes around the world. In Mexico, people consume young pads as vegetables and call them nopalitos. The production of nopalitos occurs mainly around Mexico City where cochineal insects (Dactylopius spp.) are one of the most important pests. Farmers partly control Dactylopius using insecticides, but biological control could offer a tool for the Integrated Pest Management. In this paper the cochineal insects and their natural enemies were studied in Tlalnepantla, Morelos, one of the most important regions for nopalitos production in Mexico. In order to determine Dactylopius species, 30 samples sites were selected in this region. Additionally natural enemies were collected every other week during one year period in five different zones. Dactylopius opuntiae (Cockerell) was the only cochineal species found in Tlalnepantla. The natural enemies, in order of abundance, were Leucopis bellula, Sympherobius barberi, Laetilia coccidivora, Hyperaspis trifurcata, Salpingogaster cochenillivorus, Sympherobius angustus, and Chilocorus cacti. We also included some lab and field biology descriptions of these predators. Diverse factors of crop management appeared to affect D. opuntiae population and their natural enemies.El nopal Opuntia ficus-indica se cultiva con diversos propósitos en el mundo, mientras que en México, principal productor y consumidor mundial, particularmente se consume como verdura (nopalitos). La producción de nopalitos se ubica, principalmente, en los alrededores de la Ciudad de México donde las cochinillas silvestres Dactylopius spp. son de los insectos más nocivos para el cultivo. El control químico es el método de más uso por los productores, aunque el control biológico podría ser útil para un manejo integrado de plagas. No obstante, los estudios taxonómicos sobre las especies de cochinilla y sus enemigos naturales en México no son abundantes. En esta investigación se planteó conocer las especies presentes de Dactylopius y sus enemigos naturales en Tlalnepantla, Morelos, una de las áreas de mayor producción de nopalitos en México. Se seleccionaron 30 sitios distribuidos en esta región y se establecieron cinco sitios para monitoreo de enemigos naturales cada dos semanas durante un año. La única especie de cochinilla silvestre del nopal que se encontró correspondió a Dactylopius opuntiae (Cockerell), los enemigos naturales en orden de abundancia fueron Leucopis bellula, Sympherobius barberi, Laetilia coccidivora, Hyperaspis trifurcata, Salpingogaster cochenillivorus, Sympherobius angustus y Chilocorus cacti. Se proporcionan descripciones de biología de los enemigos naturales en campo y laboratorio. Diversos factores relacionados con el manejo del cultivo tuvieron un efecto sobre las poblaciones de D. opuntiae y sus enemigos naturales