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TOI-2015 b: a sub-Neptune in strong gravitational interaction with an outer non-transiting planet

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arXiv 2025年

作者： Barkaoui, K. Korth, J. Gaidos, e. Agol, e. Parviainen, H. Pozuelos, F.J. Palle, e. Narita, N. Grimm, S. Brady, M. Bean, J.L. Morello, G. Rackham, B.V. Burgasser, A.J. Van Grootel, V. Rojas-Ayala, B. Seifahrt, A. Marfil, e. Passegger, V.M. Stalport, M. Gillon, M. Collins, K.A. Shporer, A. Giacalone, S. Yalçınkaya, S. Ducrot, e. Timmermans, M. Triaud, A.H.M.J. de Wit, J. Soubkiou, A. Watkins, C.N. Aganze, C. Alonso, R. Amado, P.J. Basant, R. Baştürk, Ö. Benkhaldoun, Z. Burdanov, A. Calatayud-Borras, Y. Chouqar, J. Conti, D.M. Collins, K.I. Davoudi, F. Delrez, L. Dressing, C.D. de Leon, J. Dévora-Pajares, M. Demory, B.O. Dransfield, G. esparza-Borges, e. Fernández-Rodriguez, G. Fukuda, I. Fukui, A. Gallardo, P.P.M. Garcia, L. Garcia, N.A. Ghachoui, M. Geraldía-González, S. Chew, Y. Gómez Maqueo González-Rodríguez, J. Günther, M.N. Hayashi, Y. Horne, K. Hooton, M.J. Hsu, C.C. Ikuta, K. Isogai, K. Jehin, e. Jenkins, J.M. Kawauchi, K. Kagetani, T. Kawai, Y. Kasper, D. Kielkopf, J.F. Klagyivik, P. Lacedelli, G. Latham, D.W. Libotte, F. Luque, R. Livingston, J.H. Mancini, L. Massey, B. Mori, M. Torres, S. Muñoz Murgas, F. Niraula, P. Orell-Miquel, J. Rapetti, David Rebolo-López, R. Ricker, G. Papini, R. Pedersen, P.P. Peláez-Torres, A. Pérez-Prieto, J.A. Poultourtzidis, e. Rodriguez, P.M. Queloz, D. Savel, A.B. Schanche, N. Sánchez-Benavente, M. Sibbald, L. Sefako, R. Sohy, S. Sota, A. Schwarz, R.P. Seager, S. Sebastian, D. Southworth, J. Stangret, M. Stefánsson, G. Stürmer, J. Srdoc, G. Thompson, S.J. Terada, Y. Vanderspek, R. Wang, G. Watanabe, N. Wilkin, F.P. Winn, J. Wells, R.D. Ziegler, C. Zúñiga-Fernández, S. Astrobiology Research Unit Université de Liège Allée du 6 Août 19C LiègeB-4000 Belgium Department of Earth Atmospheric and Planetary Science Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Calle Vía Láctea s/n Tenerife La Laguna38200 Spain Lund Observatory Division of Astrophysics Department of Physics Lund University Box 118 Lund22100 Sweden Department of Earth Sciences University of Hawaii at Manoa 1680 East-West Rd HonoluluHI96822 United States Institute for Astrophysics University of Vienna Türkenschanzstrasse 17 ViennaA-1180 Austria Department of Astronomy Astrobiology Program University of Washington Box 351580 SeattleWA98195 United States NExSS Virtual Planetary Laboratory University of Washington Box 351580 SeattleWA98195 United States Tenerife La LagunaE-38206 Spain Glorieta de la Astronomía s/n Granada18008 Spain INAF- Palermo Astronomical Observatory Piazza del Parlamento 1 Palermo90134 Italy Komaba Institute for Science The University of Tokyo 3-8-1 Komaba Meguro Tokyo153-8902 Japan Astrobiology Center 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Research Institute for Advanced Computer Science Universities Space Research Association WashingtonDC20024 United States Institute for Particle Physics and Astrophysics ETH Zürich OttoStern-Weg 5 Zürich8093 Switzerland Department of Astrophysics University of Zürich Winterthurerstrasse 190 Zürich8057 Switzerland Department of Astronomy & Astrophysics University of Chicago ChicagoIL United States NHFP Sagan Fellow United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Institute Université de Liège Allée du 6 Août 19C LiègeB-4000 Belgium Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile Gemini Observatory NSF NOIRLab 670 N. A’ohoku Place HiloHI96720 United States Departamento de

TOI-2015 is a known exoplanetary system around an M4 dwarf star, consisting of a transiting sub-Neptune planet in a 3.35-day orbital period, TOI-2015 b, accompanied by a non-transiting companion, TOI-2015 c. High-precision radial velocity measurements were taken with the MAROON-X spectrograph, and high-precision photometric data were collected, primarily using the SPeCULOOS, MUSCAT, TRAPPIST and LCOGT networks. We collected 63 transit light curves and 49 different transit epochs for TOI-2015 b. We re-characterize the target star by combining optical spectra obtained by the MAROON-X, Shane/KAST and IRTF/SpeX spectrographs, Bayesian Model Averaging (BMA) and Spectral energy Distribution (SeD) analysis. The TOI-2015 host star is a K = 10.3 mag M4-type dwarf with a sub-solar metallicity of [e/H]= −0.31 ± 0.16, and an effective temperature of Teff ≈ 3200 K. Our photodynamical analysis of the system strongly favors the 5:3 mean motion resonance and in this scenario the planet b (TOI-2015 b) has an orbital period of Pb = 3.34 days, a mass of Mp = 9.02+0.32−0.36 M⊗, a radius of Rp = 3.309+0.013−0.11 R⊗, resulting in a density of ρp = 0.25±0.01 ρ⊗ = 1.40±0.06 g cm−3, indicative of a Neptune-like composition. Its transits exhibit large (> 1 hr) timing variations indicative of an outer perturber in the system. We performed a global analysis of the high-resolution radial-velocity measurements, the photometric data, and the TTVs, and inferred that TOI-2015 hosts a second planet, TOI-2015 c, in a non-transiting configuration. Our analysis places it near a 5:3 resonance with an orbital period of Pc = 5.583 days and a mass of Mp = 8.91+0.38−0.40 M⊗. The dynamical configuration of TOI-2015 b and TOI-2015 c can be used to constrain the system’s planetary formation and migration history. Based on the mass-radius composition models, TOI-2015 b is a water-rich or rocky planet with a hydrogen-helium envelope. Moreover, TOI-2015 b has a high transmission spectroscopic metric (TSM= 149), m

关键词： Stars

A comparative analysis of transient finite-strain coupled diffusion-deformation theories for hydrogels

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arXiv 2024年

作者： Urrea-Quintero, Jorge-Humberto Marino, Michele Wick, Thomas Nackenhorst, Udo Leibniz University Hannover IBNM - Institute of Mechanics and Computational Mechanics Appelstraße 9a Hannover Lower Saxony30167 Germany Technische Universtität Braunschweig iRMB - Institute for Computational Modeling in Civil Engineering Pockelsstr. 3 Braunschweig Lower Saxony38106 Germany Department of Civil Engineering and Computer Science Engineering University of Rome Tor Vergata Via del Politecnico 1 Rome00133 Italy Leibniz University Hannover Institut für Angewandte Mathematik Welfengarten 1 Hannover Lower Saxony30167 Germany

This work presents a comparative review and classification between some well-known thermodynamically consistent models of hydrogel behavior in a large deformation setting, specifically focusing on solvent absorption/desorption and its impact on mechanical deformation and network swelling. The proposed discussion addresses formulation aspects, general mathematical classification of the governing equations, and numerical implementation issues based on the finite element method. The theories are presented in a unified framework demonstrating that, despite not being evident in some cases, all of them follow equivalent thermodynamic arguments. A detailed numerical analysis is carried out where Taylor-Hood elements are employed in the spatial discretization to satisfy the inf-sup condition and to prevent spurious numerical oscillations. The resulting discrete problems are solved using the FeniCS platform through consistent variational formulations, employing both monolithic and staggered approaches. We conduct benchmark tests on various hydrogel structures, demonstrating that major differences arise from the chosen volumetric response of the hydrogel. The significance of this choice is frequently underestimated in the state-of-the-art literature but has been shown to have substantial implications on the resulting hydrogel behavior. © 2024, CC BY.

关键词： Finite element method

Galactic transient sources with the Cherenkov Telescope Array Observatory

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Monthly Notices of the Royal Astronomical Society 2025年第1期540卷 205–238页

作者： Abe, K Abe, S Abhir, J Abhishek, A Acero, F Acharyya, A Adam, R Aguasca-Cabot, A Agudo, I Aguirre-Santaella, A Alfaro, J Alfaro, R Alvarez-Crespo, N Alves Batista, R Amans, J-P Amato, e Ambrosi, G Ambrosino, F Angüner, e O Antonelli, L A Aramo, C Arcaro, C Arnesen, T T H Asano, K Ascasibar, Y Aschersleben, J Ashkar, H Augusto Stuani, L Baack, D Backes, M Balazs, C Balbo, M Baquero Larriva, A Barbosa Martins, V Barres de Almeida, U Barrio, J A Barrios-Jiménez, L Batković, I Batzofin, R Baxter, J Becerra González, J Becker Tjus, J Belmont, R Benbow, W Bernete, J Bernlöhr, K Berti, A Bertucci, B Beshley, V Bhattacharjee, P Bhattacharyya, S Bigongiari, C Bissaldi, e Blanch, O Blazek, J Bocchino, F Boisson, C Bolmont, J Bonnoli, G Bonollo, A Bordas, P Bosnjak, Z Bottacini, e Böttcher, M Bradascio, F Bronzini, e Brown, A M Brunelli, G Bulgarelli, A Burelli, I Burger-Scheidlin, C Burmistrov, L Burton, M Buscemi, M Cailleux, J Campoy-Ordaz, A Cantlay, B K Capasso, G Caproni, A Capuzzo-Dolcetta, R Caraveo, P Caroff, S Carosi, A Carosi, R Carquin, e Carrasco, M-S Cascone, e Cassol, F Castaldini, L Castrejon, N Castro-Tirado, A J Cerasole, D Ceribella, G Cerruti, M Chadwick, P M Chaty, S Chen, A W Chernyakova, M Chiavassa, A Chudoba, J Chytka, L Cicciari, G M Cifuentes, A Coimbra Araujo, C H Colapietro, M Conforti, V Contreras, J L Cortina, J Costa, A Costantini, H Cotter, G Cristofari, P Cuevas, O Curtis-Ginsberg, Z D’Aì, A D’Amico, G D’Ammando, F Dai, S Dazzi, F de Bony de Lavergne, M De Caprio, V De Cesare, G De Frondat Laadim, F de Gouveia Dal Pino, e M De Lotto, B De Lucia, M de Martino, D de Menezes, R de Naurois, M de Ona Wilhelmi, e de Souza, V del Peral, L del Valle, M V Delgado, C Dell’aiera, M Della Valle, M della Volpe, D Depaoli, D Devin, J Di Girolamo, T Di Piano, A Di Pierro, F Di Tria, R Di Venere, L Diebold, S Dignam, C Dima, R Dinesh, A Djuvsland, J Dominik, R M Dominis Prester, D Donini, A Dorner, D Dörner, J Doro, M Dubos, C Ducci, L Dwarkadas, V V ebr, J eckner, C egberts, K einecke, S elsässer, D emery Department of Physics Tokai University 4-1-1 Kita-Kaname Hiratsuka Kanagawa 259-1292 Japan Institute for Cosmic Ray Research University of Tokyo 5-1-5 Kashiwa-no-ha Kashiwa Chiba 277-8582 Japan ETH Zürich Institute for Particle Physics and Astrophysics Otto-Stern-Weg 5 CH-8093 Zürich Switzerland INFN and Università degli Studi di Siena Dipartimento di Scienze Fisiche della Terra e dell’Ambiente (DSFTA) Sezione di Fisica Via Roma 56 I-53100 Siena Italy Université Paris-Saclay Université Paris Cité CEA CNRS AIM F-91191 Gif-sur-Yvette Cedex France FSLAC IRL 2009 CNRS/IAC E-38205 La Laguna Tenerife Spain University of Alabama Tuscaloosa Department of Physics and Astronomy Gallalee Hall Box 870324 Tuscaloosa AL 35487-0324 USA Université Côte d’Azur Observatoire de la Côte d’Azur CNRS Laboratoire Lagrange UF 06304 Nice France Laboratoire Leprince-Ringuet CNRS/IN2P3 École Polytechnique Institut Polytechnique de Paris F-91120 Palaiseau France Departament de Física Quàntica i Astrofísica Institut de Ciències del Cosmos Universitat de Barcelona IEEC-UB Martí i Franquès 1 E-08028 Barcelona Spain Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n E-18008 Granada Spain Institute for Computational Cosmology and Department of Physics Durham University South Road Durham DH1 3LE UK Pontificia Universidad Católica de Chile Av. Libertador Bernardo O’Higgins 340 8331150 Santiago Chile Universidad Nacional Autónoma de México Delegación Coyoacán 04510 Ciudad de México Mexico IPARCOS-UCM Instituto de Física de Partículas y del Cosmos and EMFTEL Department Universidad Complutense de Madrid E-28040 Madrid Spain Instituto de Física Teórica UAM/CSIC and Departamento de Física Teórica Universidad Autónoma de Madrid c/ Nicolás Cabrera 13-15 Campus de Cantoblanco UAM E-28049 Madrid Spain LUTH GEPI and LERMA Observatoire de Paris Université PSL Université Paris Cité CNRS 5 place Jules Janssen F-92190 Meudon France INAF – Osservatorio

A wide variety of Galactic sources show transient emission at soft and hard X-ray energies: low- and high-mass X-ray binaries containing compact objects, isolated neutron stars exhibiting extreme variability as magnetars as well as pulsar-wind nebulae. Although most of them can show emission up to MeV and/or GeV energies, many have not yet been detected in the TeV domain by Imaging Atmospheric Cherenkov Telescopes. In this paper, we explore the feasibility of detecting new Galactic transients with the Cherenkov Telescope Array Observatory (CTAO) and the prospects for studying them with Target of Opportunity observations. We show that CTAO will likely detect new sources in the TeV regime, such as the massive microquasars in the Cygnus region, low-mass X-ray binaries with low-viewing angle, flaring emission from the Crab pulsar-wind nebula or other novae explosions, among others. Since some of these sources could also exhibit emission at larger time-scales, we additionally test their detectability at longer exposures. We finally discuss the multiwavelength synergies with other instruments and large astronomical facilities.

关键词： binaries: general stars: magnetars novae cataclysmic variables pulsars: general gamma-rays: general

NIPS workshop on new problems and methods in computational biology

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NIPS workshop on new problems and methods in computational b...

作者： Chechik, Gal Leslie, Christina Noble, William Stafford Rätsch, Gunnar Morris, Quaid Tsuda, Koji Computer Science Department Stanford University 353 Serra Mall Stanford CA 94305 United States Computational Biology Program Memorial Sloan-Kettering Cancer Center 1275 York Ave New York NY 10065 United States Department of Genome Sciences University of Washington 1705 NE Pacific St Seattle WA 98109 United States Friedrich Miescher Laboratory of the Max Planck Society Spemannstr. 39 72076 Tübingen Germany Terrence Donnelley Centre for Cellular and Biomolecular Research University of Toronto 160 College Street Toronto ON M5S 3E1 Canada Max Planck Institute for Biological Cybernetics Spemannstr. 38 72076 Tübingen Germany

A parallel accelerated adaptive mesh algorithm for the solution of electrical models of the heart

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International Journal of High Performance Systems Architecture 2012年第2期4卷 89-100页

作者： Oliveira, Rafael Sachetto Rocha, Bernardo M. Burgarelli, Denise Meira Jr., Wagner Dos Santos, Rodrigo Weber Department of Computer Science Federal University of São João de Rei Av. Visconde do Rio Preto s/n Col. do Bengo São João del-Rei MG 36301-360 Brazil Department of Computer Science Federal University of Minas Gerais Av. Antônio Carlos 6627 Pampulha Belo Horizonte MG 31270-010 Brazil National Laboratory for Scientific Computing Avenida Getúlio Vargas 333 Petrópolis RJ 25651-076 Brazil Department of Computer Science Federal University of Juiz de Fora Campus Universitário Rua José Kelmer S/n Bairro São Pedro Juiz de Fora MG 36036-330 Brazil Department of Mathematics Federal University of Minas Gerais Av. Antônio Carlos 6627 Pampulha Belo Horizonte MG 31270-010 Brazil Department of Computer Science e Computational Modeling Program Federal University of Juiz de Fora Campus Universitário Rua José Kelmer S/n Bairro São Pedro Juiz de Fora MG 36036-330 Brazil

computer models have become valuable tools for the study and comprehension of the complex phenomena of cardiac electrophysiology. However, the high complexity of the biophysical processes translates into complex mathematical and computational models. In this paper, we evaluate a parallel numerical algorithm based on mesh adaptivity and finite volume method aiming to accelerate these simulations. This is a very attractive approach since the spreading electrical wavefront corresponds only to a small fraction of the cardiac tissue. Usually, the numerical solution of the partial differential equations that model the phenomenon requires very fine spatial discretisation to follow the wavefront, which is approximately 0.2 mm. The use of uniform meshes leads to high computational cost as it requires a large number of mesh points. In this sense, the tests reported in this work show that simulations of two-dimensional models of cardiac tissue have been accelerated by more than 340 times using the adaptive mesh algorithm and parallel computing, with no significant loss in accuracy. Copyright © 2012 Inderscience enterprises Ltd.

关键词： Wavefronts

Considering discrepancy when calibrating a mechanistic electrophysiology model

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arXiv 2020年

作者： Lei, Chon Lok Ghosh, Sanmitra Whittaker, Dominic G. Aboelkassem, Yasser Beattie, Kylie A. Cantwell, Chris D. Delhaas, Tammo Houston, Charles Novaes, Gustavo Montes Panfilov, Alexander V. Pathmanathan, Pras Riabiz, Marina Weber dos Santos, Rodrigo Worden, Keith Mirams, Gary R. Wilkinson, Richard D. Computational Biology & Health Informatics Dept. of Computer Science University of Oxford United Kingdom MRC Biostatistics Unit University of Cambridge United Kingdom Centre for Mathematical Medicine & Biology School of Mathematical Sciences University of Nottingham United Kingdom Department of Bioengineering University of California San Diego United States Systems Modeling and Translational Biology GlaxoSmithKline R&D Stevenage United Kingdom ElectroCardioMaths Programme Centre for Cardiac Engineering Imperial College London United Kingdom CARIM School for Cardiovascular Diseases Maastricht University Netherlands Graduate Program in Computational Modeling Universidade Federal de Juiz de Fora Brazil Department of Physics and Astronomy Ghent University Belgium Laboratory of Computational Biology and Medicine Ural Federal University Ekaterinburg Russia U.S. Food and Drug Administration Center for Devices and Radiological Health Office of Science and Engineering Laboratories United States Department of Biomedical Engineering King’s College London Alan Turing Institute United Kingdom Dynamics Research Group Department of Mechanical Engineering University of Sheffield United Kingdom School of Mathematics and Statistics University of Sheffield United Kingdom

Uncertainty quantification (UQ) is a vital step in using mathematical models and simulations to take decisions. The field of cardiac simulation has begun to explore and adopt UQ methods to characterise uncertainty in model inputs and how that propagates through to outputs or predictions. In this perspective piece we draw attention to an important and under-addressed source of uncertainty in our predictions — that of uncertainty in the model structure or the equations themselves. The difference between imperfect models and reality is termed model discrepancy, and we are often uncertain as to the size and consequences of this discrepancy. Here we provide two examples of the consequences of discrepancy when calibrating models at the ion channel and action potential scales. Furthermore, we attempt to account for this discrepancy when calibrating and validating an ion channel model using different methods, based on modelling the discrepancy using Gaussian processes (GPs) and autoregressive-moving-average (ARMA) models, then highlight the advantages and shortcomings of each approach. Finally, suggestions and lines of enquiry for future work are provided. Copyright © 2020, The Authors. All rights reserved.

关键词： Uncertainty analysis

Detecting anomalous citation groups in journal networks

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arXiv 2020年

作者： Kojaku, Sadamori Livan, Giacomo Masuda, Naoki Luddy School of Informatics Computing and Engineering Indiana University BloomingtonIN47408 United States Department of Computer Science University College London LondonWC1E 6EA United Kingdom Systemic Risk Centre London School of Economics and Political Science LondonWC2A 2AE United Kingdom Department of Mathematics University at Buffalo State University of New York BuffaloNY United States Computational and Data-Enabled Science and Engineering Program University at Buffalo State University of New York BuffaloNY14260-2900 United States Faculty of Science and Engineering Waseda University Tokyo169-8555 Japan

The ever-increasing competitiveness in the academic publishing market incentivizes journal editors to pursue higher impact factors. This translates into journals becoming more selective, and, ultimately, into higher publication standards. However, the fixation on higher impact factors leads some journals to artificially boost impact factors through the coordinated effort of a "citation cartel" of journals. "Citation cartel" behavior has become increasingly common in recent years, with several instances being reported. Here, we propose an algorithm—-named CIDRe—to detect anomalous groups of journals that exchange citations at excessively high rates when compared against a null model that accounts for scientific communities and journal size. CIDRe detects more than half of the journals suspended from Journal Citation Reports due to anomalous citation behavior in the year of suspension or in advance. Furthermore, CIDRe detects many new anomalous groups, where the impact factors of the member journals are lifted substantially higher by the citations from other member journals. We describe a number of such examples in detail and discuss the implications of our findings with regard to the current academic climate. Copyright © 2020, The Authors. All rights reserved.

关键词： Publishing

Best practices for machine learning in antibody discovery and development

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arXiv 2023年

作者： Wossnig, Leonard Furtmann, Norbert Buchanan, Andrew Kumar, Sandeep Greiff, Victor LabGenius Ltd. The Biscuit Factory 100 Drummond Road London LondonSE16 4DG United Kingdom Department of Computer Science University College London 66-72 Gower St LondonWC1E 6EA United Kingdom R&D Large Molecules Research Platform Sanofi Deutschland GmbH Industriepark Höchst Frankfurt am Main Germany Biologics Engineering R&D AstraZeneca CambridgeCB2 0AA United Kingdom Computational Protein Design and Modeling Group Computational Science Moderna Therapeutics 200 Technology Square CambridgeMA02139 United States Department of Immunology Oslo University Hospital University of Oslo Oslo Norway

Over the past 40 years, the discovery and development of therapeutic antibodies to treat disease has become common practice. However, as therapeutic antibody constructs are becoming more sophisticated (e.g., multi-specifics), conventional approaches to optimisation are increasingly inefficient. Machine learning (ML) promises to open up an in silico route to antibody discovery and help accelerate the development of drug products using a reduced number of experiments and hence cost. Over the past few years, we have observed rapid developments in the field of ML-guided antibody discovery and development (D&D). However, many of the results are difficult to compare or hard to assess for utility by other experts in the field due to the high diversity in the datasets and evaluation techniques and metrics that are across industry and academia. This limitation of the literature curtails the broad adoption of ML across the industry and slows down overall progress in the field, highlighting the need to develop standards and guidelines that may help improve the reproducibility of ML models across different research groups. To address these challenges, we set out in this perspective to critically review current practices, explain common pitfalls, and clearly define a set of method development and evaluation guidelines that can be applied to different types of ML-based techniques for therapeutic antibody D&D. Specifically, we address in an end-to-end analysis, challenges associated with all aspects of the ML process and recommend a set of best practices for each stage. © 2023, CC BY-NC-ND.

关键词： Antibodies

FIeLD SAMPLING OF ReSIDUAL AVIATION GASOLINe IN SANDY SOIL

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GROUND WATeR MONITORING AND ReMeDIATION 1991年第2期11卷 107-120页

作者： OSTeNDORF, DW LeACH, Le HINLeIN, eS XIe, YF 1 David W. Ostendorf is an associate professor in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Dr. Ostendorf is a registered professional engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Water Well Association.2 Lowell E. Leach is an environmental engineer with the Robert S. Kerr Environmental Research Laboratory of the U.S. Environmental Protection Agency (RS Kerr Environmental Research Laboratory U.S. EPA P.O. Box 1198 Ada OK74820). Leach received his B.S. ingeological engineering at the University of Oklahoma in 1959 and has been a registered professional engineer in Oklahoma since 1966. With 29 years of experience in field applications of geological engineering he is responsible for developing methodology for sampling ground water and subsurface materials for the Robert S. Kerr Environmental Research Laboratory.3 Erich S. Hinlein is a research assistant in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include ground water pollution hazardous waste site investigation and transport processes in unconfined aquifers. Hinlein graduated with a B.S. in electrical and computer engineering from the University of Massachusetts at Amherst in May 1985 and entered the Environmental Engineering Master's Degree Program in January 1989.4 Yuefeng Xie is a postdoctoral research associate in the Environmental Engineering Program of the Civil E

Two complementary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured field extrusion of core barrels into pint-size Mason jars, while the second consisted of laboratory partitioning of intact stainless steel core sleeves. The barrel extrusion procedure involved jar headspace sampling in a nitrogen-filled glove box, which delineated the 0.7m thick residually contaminated interval for subsequent core sleeve withdrawal from adjacent boreholes. Soil samples removed from the Mason jars (in the field) and sleeve segments (in the laboratory) were subjected to methylene chloride extraction and gas chromatographic analysis to compare their aviation gasoline content. The barrel extrusion sampling method yielded a vertical profile with 0.10m resolution over an essentially continuous 5.0m interval from the ground surface to the water table. The sleeve segment alternative yielded a more resolved 0.03m vertical profile over a shorter 0.8m interval through the capillary fringe. The two methods delivered precise estimates of the vertically integrated mass of aviation gasoline at a given horizontal location, and a consistent view of the vertical profile as well. In the latter regard, a 0.2m thick lens of maximum contamination was found in the center of the capillary fringe, where moisture filled all voids smaller than the mean pore size. The maximum peak was resolved by the core sleeve data, but was partially obscured by the barrel extrusion observations, so that replicate barrels or a half-pint Mason jar size should be considered for data supporting vertical transport analyses in the absence of sleeve partitions.

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