Pileup Mitigation with Machine Learning (PUMML)

Pileup involves the contamination of the energy distribution arising from the primary collision of interest (leading vertex) by radiation from soft collisions (pileup). We develop a new technique for removing this contamination using machine learning and convolutional neural networks. The network takes as input the energy distribution of charged leading vertex particles, charged pileup particles, and all neutral particles and outputs the energy distribution of particles coming from leading vertex alone. The PUMML algorithm performs remarkably well at eliminating pileup distortion on a wide range of simple and complex jet observables. We test the robustness of the algorithm in a number of ways and discuss how the network can be trained directly on data.Comment: 20 pages, 8 figures, 2 tables. Updated to JHEP versio

Learning to Classify from Impure Samples with High-Dimensional Data

A persistent challenge in practical classification tasks is that labeled training sets are not always available. In particle physics, this challenge is surmounted by the use of simulations. These simulations accurately reproduce most features of data, but cannot be trusted to capture all of the complex correlations exploitable by modern machine learning methods. Recent work in weakly supervised learning has shown that simple, low-dimensional classifiers can be trained using only the impure mixtures present in data. Here, we demonstrate that complex, high-dimensional classifiers can also be trained on impure mixtures using weak supervision techniques, with performance comparable to what could be achieved with pure samples. Using weak supervision will therefore allow us to avoid relying exclusively on simulations for high-dimensional classification. This work opens the door to a new regime whereby complex models are trained directly on data, providing direct access to probe the underlying physics.Comment: 6 pages, 2 tables, 2 figures. v2: updated to match PRD versio

Escape Rates in a Stochastic Environment with Multiple Scales

We consider a stochastic environment with two time scales and outline a general theory that compares two methods to reduce the dimension of the original system. The first method involves the computation of the underlying deterministic center manifold followed by a naive replacement of the stochastic term. The second method allows one to more accurately describe the stochastic effects and involves the derivation of a normal form coordinate transform that is used to find the stochastic center manifold. The results of both methods are used along with the path integral formalism of large fluctuation theory to predict the escape rate from one basin of attraction to another. The general theory is applied to the example of a surface flow described by a generic, singularly perturbed, damped, nonlinear oscillator with additive, Gaussian noise. We show how both nonlinear reduction methods compare in escape rate scaling. Additionally, the center manifolds are shown to predict high pre-history probability regions of escape. The theoretical results are confirmed using numerical computation of the mean escape time and escape prehistory, and we briefly discuss the extension of the theory to stochastic control.Comment: 32 pages, 8 figures, Final revision to appear in SIAM Journal on Applied Dynamical System

Giving patients granular control of personal health information: Using an ethics ‘Points to Consider’ to inform informatics system designers

Objective: There are benefits and risks of giving patients more granular control of their personal health information in electronic health record (EHR) systems. When designing EHR systems and policies, informaticists and system developers must balance these benefits and risks. Ethical considerations should be an explicit part of this balancing. Our objective was to develop a structured ethics framework to accomplish this. Methods: We reviewed existing literature on the ethical and policy issues, developed an ethics framework called a “Points to Consider” (P2C) document, and convened a national expert panel to review and critique the P2C. Results: We developed the P2C to aid informaticists designing an advanced query tool for an electronic health record (EHR) system in Indianapolis. The P2C consists of six questions (“Points”) that frame important ethical issues, apply accepted principles of bioethics and Fair Information Practices, comment on how questions might be answered, and address implications for patient care. Discussion: The P2C is intended to clarify whatis at stake when designers try to accommodate potentially competing ethical commitments and logistical realities. The P2C was developed to guide informaticists who were designing a query tool in an existing EHR that would permit patient granular control. While consideration of ethical issues is coming to the forefront of medical informatics design and development practices, more reflection is needed to facilitate optimal collaboration between designers and ethicists. This report contributes to that discussion

Deep learning in color: towards automated quark/gluon jet discrimination

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. To establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, the deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.Massachusetts Institute of Technology. Department of Physic

Isolated bladder metastasis causing large bowel obstruction: a case report of an atypical presentation of intussusception

Intussusception of the large bowel is a rare clinical entity. In adults, this pathology is usually associated with a malignant lead point and often requires operative management. Reported is the case of an 83-year-old female who was recently diagnosed with superficial bladder cancer (T1) treated by partial cystectomy. She presented 3 months post-operatively with an isolated mucosal metastasis of the transverse colon causing intussusception and large bowel obstruction. The patient was successfully treated by colonic resection with primary anastomosis. Histology was significant for a pedunculated sarcomatoid bladder carcinoma originating from the colonic mucosa with incomplete invasion of the bowel wall. An isolated mucosal metastasis of this variety has not been reported in the literature to date

Points to consider in ethically constructing patient-controlled electronic health records

Patient advocates and leaders in informatics have long proposed that patients should have greater ability to control the information in their electronic health record (EHR), including how it can be accessed by their health care providers. The value of such “granular” control, as it has been termed, has been supported prominently in an influential report by the President’s Council of Advisors on Science and Technology (PCAST). Recently, the U.S. Department of Health and Human Services (HHS) Office of the National Coordinator for Health Information Technology (ONC) funded several projects to study key components of EHR systems, including exploring ways to allow granular control. This “Points to Consider” document provides an overview of the benefits, risks and challenges of granular control of EHRs; a review of the key ethical principles, values, and Fair Information Practices that ought to guide development of an EHR that accommodates granular control, and seven detailed Points to Consider to guide decision making.Award No: 90HT0054/01, a cooperative agreement program from the US Department of Health and Human Services, Office of the National Coordinator for Health IT to Indiana Health Information Technology, Inc. (IHIT) under the State HIE – Challenge Grant Program to the Indiana University School of Medicine and Regenstrief Institute, Inc

An on-shell approach to factorization

Factorization is possible due to the universal behavior of Yang-Mills theories in soft and collinear limits. Here, we take a small step towards a more transparent understanding of these limits by proving a form of perturbative factorization at treelevel using on-shell spinor helicity methods. We present a concrete and self-contained expression of factorization in which matrix elements in QCD are related to products of other matrix elements in QCD up to leading order in a power-counting parameter determined by the momenta of certain physical on-shell states. Our approach uses only the scaling of momenta in soft and collinear limits, avoiding any assignment of scaling behavior to unphysical (and gauge-dependent) fields. The proof of factorization exploits many advantages of helicity spinors, such as the freedom to choose different reference vectors for polarizations in different collinear sectors. An advantage of this approach is that once factorization is shown to hold in QCD, the transition to SoftCollinear Effective Theory is effortless.Physic

Report from the PredictER Expert Panel Meeting, November 2, 2007

On November 2, 2007, the Indiana University Center for Bioethics convened an expert panel on predictive health research (PHR) as part of the Center’s Program in Predictive Health Ethics Research (http://www.bioethics.iu.edu/predicter.asp) which is supported by a grant from the Richard M. Fairbanks Foundation. The goal of this meeting was to identify the major obstacles and opportunities for engaging the community in PHR. PredictER intends to use the results of this meeting as a first step toward more fully engaging the Indianapolis community in discussions about PHR.Richard M. Fairbanks Foundatio