Articles

10/02/2021-- 01/25/2021

Design and Fabrication of Metamaterial Anti-Reflection Coatings for the Simons Observatory

The Simons Observatory (SO) will be a cosmic microwave background (CMB) survey experiment with three small-aperture telescopes and one large-aperture telescope, which will observe from the Atacama Desert in Chile. In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities, as outlined in The Simons Observatory Collaboration et al. (2019). These telescopes require 33 highly transparent, large aperture, refracting optics. To this end, we developed mechanically robust, highly efficient, metamaterial anti-reflection (AR) coatings with octave bandwidth coverage for silicon optics up to 46 cm in diameter for the 22-55, 75-165, and 190-310 GHz bands. We detail the design, the manufacturing approach to fabricate the SO lenses, their performance, and possible extensions of metamaterial AR coatings to optical elements made of harder materials such as alumina.
Joseph E. Golec Jeffrey J. McMahon Aamir M. Ali Grace E. Chesmore Leah Cooperrider Simon Dicker Nicholas Galitzki Kathleen Harrington Rebecca Jackson Benjamin Westbrook Edward J. Wollack Zhilei Xu Ningfeng Zhu
12/09/1998-- 12/09/1998

Revisting Lepton Pairs at the SPS

We confirm the importance of standard medium effects (hadronic rescattering) in heavy-ion collisions by using a pQCD-based model to investigate the dilepton spectra from Pb+Au collisions at 158 GeV/nucleon.
J. Murray W. Bauer K. Haglin
06/29/2010-- 06/29/2010

Working Document on Gloss Ontology

This document describes the Gloss Ontology. The ontology and associated class model are organised into several packages. Section 2 describes each package in detail, while Section 3 contains a summary of the whole ontology.
Joelle Coutaz Alan Dearle Sophie Dupuy-Chessa Graham Kirby Christophe Lachenal Ron Morrison Gaetan Rey Evangelos Zirintsis
10/16/2004-- 10/16/2004

Modeling of a chlorine high-density plasma submitted to a static magnetic field

This paper extends the results of a recently developed one-dimensional model aiming to describe the characteristics of a magnetized chlorine high-density plasma. In this work, the dependence of the plasma characteristics on the magnetic field intensity is investigated. It is shown that the dissociation degree and the relative weight of the various charged species is strongly influenced by the magnetic field when the gas pressure is low enough. In contrast, at higher pressure, the plasma is essentially composed of negative ions, and molecular neutrals and ions, independently of the field intensity. It is further demonstrated that diffusion needs to be considered in order to correctly predict the plasma behavior.
Jean-Sebastien Poirier Luc Stafford Joelle Margot Francois Vidal Karl Giroux Antoine Quintal-Leonard Mohamed Chaker
10/18/2004-- 10/18/2004

Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure

This work presents a few preliminary results from a collisional-radiative (CR) model intended to describe an argon microwave (2.45 GHz) plasma at atmospheric pressure. This model aims to investigate the influence of dissociative recombination products on the Saha-Boltzmann plasma equilibrium. The model is tested through comparison with experimental results obtained in an argon plasma column generated by a traveling electromagnetic surface-wave, which is suitable to perform a parametric investigation of the plasma. It is shown that dissociative recombination predominantly populates the 4s levels and the ground state. It is further observed that it strongly influences the population of the levels, specially those of lower energy. However, the higher levels (close to the ionization limit) appear to be in equilibrium whatever the plasma density. This allows assuming that the excitation temperature Texc determined from the upper levels in the atomic system in the Boltzmann-plot is equal to Te.
Abel Sainz Joelle Margot Maria Carmen Garcia Maria Dolores Calzada
04/22/2014-- 04/22/2014

A Logical Framework for Systems Biology

We propose a novel approach for the formal verification of biological systems based on the use of a modal linear logic. We show how such a logic can be used, with worlds as instants of time, as an unified framework to encode both biological systems and temporal properties of their dynamic behaviour. To illustrate our methodology, we consider a model of the P53/Mdm2 DNA-damage repair mechanism. We prove several properties that are important for such a model to satisfy and serve to illustrate the promise of our approach. We formalize the proofs of these properties in the Coq Proof Assistant, with the help of a Lambda Prolog prover for partial automation of the proofs.
Elisabetta De Maria Joelle Despeyroux Amy Felty
01/18/2017-- 01/18/2017

(Mathematical) Logic for Systems Biology (Invited Paper)

We advocates here the use of (mathematical) logic for systems biology, as a unified framework well suited for both modeling the dynamic behaviour of biological systems, expressing properties of them, and verifying these properties. The potential candidate logics should have a traditional proof theoretic pedigree (including a sequent calculus presentation enjoying cut-elimination and focusing), and should come with (certified) proof tools. Beyond providing a reliable framework, this allows the adequate encodings of our biological systems. We present two candidate logics (two modal extensions of linear logic, called HyLL and SELL), along with biological examples. The examples we have considered so far are very simple ones-coming with completely formal (interactive) proofs in Coq. Future works includes using automatic provers, which would extend existing automatic provers for linear logic. This should enable us to specify and study more realistic examples in systems biology, biomedicine (diagnosis and prognosis), and eventually neuroscience.
Joëlle Despeyroux
02/07/2015-- 02/07/2015

Coupled effects of applied load and surface structure on the viscous forces during peeling

Tree frogs are able take advantage of an interconnected network of epithelial cells in their toe pads to modulate their adhesion to surfaces under dry, wet, and flooded environments. It has been hypothesized that these interconnected drainage channels reduce the hydrodynamic repulsion to facilitate contact under a completely submerged environment (flooded conditions). Using a custom-built apparatus we investigate the interplay between surface structure and loading conditions on the peeling force. By combining a normal approach and detachment by peeling we can isolate the effects of surface structure from the loading conditions. We investigate three surfaces: two rigid structured surfaces that consist of arrays of cylindrical posts and a flat surface as a control. We observe three regimes in the work required to separate the structured surface that depend on the fluid film thickness prior to pull out. These three regimes are based on hydrodynamics and our experimental results agree with a simple scaling argument that relates the surface features to the different regimes observed. Overall we find that the work of separation of a structured surface is always less than or equal to the one for a smooth surface when considering purely viscous contributions.
Charles Dhong Joelle Frechette
08/01/2023-- 08/01/2023

Exploiting the dynamics of commodity futures curves

The Nelson-Siegel framework is employed to model the term structure of commodity futures prices. Exploiting the information embedded in the level, slope and curvature parameters, we develop novel investment strategies that assume short-term continuation of recent parallel, slope or butterfly movements of futures curves. Systematic strategies based on the change in the slope generate significant profits that are unrelated to previously documented risk factors and can survive reasonable transaction costs. Further analysis demonstrates that the profitability of the slope strategy increases with investor sentiment and is in part a compensation for the drawdowns incurred during economic slowdowns. The profitability can also be magnified through timing and persists under alternative specifications of the Nelson-Siegel model.
Robert J Bianchi John Hua Fan Joelle Miffre Tingxi Zhang
04/15/2025-- 04/15/2025

SAR-to-RGB Translation with Latent Diffusion for Earth Observation

Earth observation satellites like Sentinel-1 (S1) and Sentinel-2 (S2) provide complementary remote sensing (RS) data, but S2 images are often unavailable due to cloud cover or data gaps. To address this, we propose a diffusion model (DM)-based approach for SAR-to-RGB translation, generating synthetic optical images from SAR inputs. We explore three different setups: two using Standard Diffusion, which reconstruct S2 images by adding and removing noise (one without and one with class conditioning), and one using Cold Diffusion, which blends S2 with S1 before removing the SAR signal. We evaluate the generated images in downstream tasks, including land cover classification and cloud removal. While generated images may not perfectly replicate real S2 data, they still provide valuable information. Our results show that class conditioning improves classification accuracy, while cloud removal performance remains competitive despite our approach not being optimized for it. Interestingly, despite exhibiting lower perceptual quality, the Cold Diffusion setup performs well in land cover classification, suggesting that traditional quantitative evaluation metrics may not fully reflect the practical utility of generated images. Our findings highlight the potential of DMs for SAR-to-RGB translation in RS applications where RGB images are missing.
Kaan Aydin Joelle Hanna Damian Borth


with thanks to arxiv.org/