Front dynamics during diffusion-limited corrosion of ramified electrodeposits

Experiments on the diffusion-limited corrosion of porous copper clusters in thin gap cells containing cupric chloride are reported. By carefully comparing corrosion front velocities and concentration profiles obtained by phase-shift interferometry with theoretical predictions, it is demonstrated that this process is well-described by a one-dimensional mean-field model for the generic reaction A + B (static) -> C (inert) with only diffusing reactant (cupric chloride) and one static reactant (copper) reacting to produce an inert product (cuprous chloride). The interpretation of the experiments is aided by a mathematical analysis of the model equations which allows the reaction-order and the transference number of the diffusing species to be inferred. Physical arguments are given to explain the surprising relevance of the one-dimensional mean-field model in spite of the complex (fractal) structure of the copper clusters.Comment: 26 pages, 10 figures, submitted to J. Phys. Chem. B, high quality eps figures available at http://www-math.mit.edu/~bazant/paper

METAMORPHISM, KINEMATIC EVOLUTION, AND TIMING CONSTRAINTS OF THE GREENBRIER FAULT AROUND THE ELA AND BRYSON CITY DOMES, NORTH CAROLINA

Field mapping, microstructural analysis, and electron microprobe analysis were performed on rocks from the Bryson City and Ela domes, North Carolina, to help constrain the tectonic history of the region. The domes are en echelon northeast-trending antiformal structures formed by two perpendicular sets of folds. They are bounded by the Greenbrier fault, which forms a ductile shear zone that juxtaposes the Great Smoky Group in the hanging wall with Grenville basement in the footwall. Isoclinal folds (F2) and axial planar foliation (S2) characterize the regional deformation (D2). Inter- to syn-kinematic porphyroblasts (relative to D2) of kyanite, staurolite, and garnet grew during Taconic Barrovian metamorphism (M2). Compositional maps of garnet yield Ca and Mn zoning patterns that are consistent with multiple stages of garnet growth. Pressure-temperature estimates, calculated using THERMOCALC v3.33, indicate that the Great Smoky Group reached conditions of 667 degrees Celsius and 9.2 kbar. A high-strain mylonite zone (S2b) near the contact between the Great Smoky Group and the Greenville basement is parallel to the regional foliation (S2). Mineral stretching lineations trend northeast-southwest around the margins of both domes. Rotated porphyroblasts indicate that shear zone formation (S2b) post-dated Barrovian metamorphism. Quartz deformation mechanisms record shearing (D2) of the Greenbrier fault at 500-600 degrees Celsius. Shear sense indicators record top-to-the-northeast displacement that predates doming, consistent with orogen-parallel transport during this stage of deformation. A subsequent deformation event (D3) created open to tight isoclinal folds (F3) and a pervasive axial planar cleavage development (S3) that overprints earlier fabric. Brittle faults record the final stage of deformation (D4). Kyanite alteration to sericite or white mica and chlorite replacement of biotite and garnet is attributed to a post-kinematic, retrograde metamorphic event (M4). These data demonstrate that the ductile portion of the Greenbrier fault around the Ela and Bryson City domes accommodated orogen-parallel transport during the late Taconic orogeny

Contamination of spacecraft by recontact of dumped liquids

Liquids partially freeze when dumped from spacecraft producing particles which are released into free space at various velocities. Recontact of these particles with the spacecraft is possible for specific particle sizes and velocities and, therefore, can become contamination for experiments within the spacecraft or released experiments as a result of waste and potable water dumped from Space Shuttle. An examination of dump characteristics was conducted on STS-29 using both on-board video records and ground based measurements. A preliminary analysis of data from this flight indicates particle velocities are in the range of 30 to 75 ft/sec and recontact is possible for limited particle sizes

Vertical Assessment of Lidar Bathymetry

Validation of Airborne Light Detection And Ranging (LiDAR) Bathymetry (ALB) is necessary for the production of nautical charts to fill coastal charting gaps and to quickly and accurately measure shallow dynamic seafloors. Previous assessments concentrate on the validation of ALB data within overlapping regions of Multibeam Echo-Sounder (MBES) data. This paper presents new coverage environments to the MBES overlap validation method, and proposes an alternative method for comparison between ALB data and ENC vector information. Analysis of the validation methods favour comparisons using overlapping MBES data; however, the overlap of ALB and ENC information provides an additional assessment method with substantial overlapping regions. The ENC comparison proves to be useful at locations where MBES data is absent and in the assessment of chart adequacy.La validación de la batimetría mediante la detección y el alcance de la luz aerotransportada (LiDAR – Light Detection And Ranging) es necesaria para que la producción de cartas náuticas complete los vacíos de la cartografía costera y mida con rapidez y precisión los fondos marinos dinámicos poco profundos. Las evaluaciones anteriores se concentran en la validación de los datos ALB en el seno de las regiones de solapamiento de los datos de la Ecosonda Multihaz (MBES). Este documento presenta nuevos entornos de cobertura para el método de validación mediante el solapamiento MBES, y propone un método alternativo para la comparación entre los datos del ALB y la información vectorial de las ENCs. El análisis de los métodos de validación favorece las comparaciones utilizando los datos de solapamiento MBES; sin embargo, el solapamiento de la información ALB y ENC proporciona un método de evaluación adicional con importantes regiones de solapamiento. La comparación de las ENCs resulta útil en los lugares en que no hay datos MBES y en la evaluación de la idoneidad de las cartas.La validation des données bathymétriques issues de levés LiDAR (Light Detection And Ranging, en français : détection et estimation de la distance par la lumière) aéroporté (ALB) est nécessaire pour la production de cartes marines afin de combler les trous dans la cartographie côtière et de mesurer rapidement et efficacement l’évolution des planchers océaniques peu profonds. Les évaluations précédentes étaient axées sur la validation de données ALB au sein de régions où des données issues de sondages acoustiques multifaisceaux (SMF) se chevauchaient. Le présent article présente les nouvelles conditions de couverture de la méthode de validation par recoupement des données SMF, et propose une méthode alternative de comparaison entre les données ALB et les informations vectorielles des ENC. L’analyse de ces méthodes de validation favorise les comparaisons utilisant le recoupement des données SMF ; toutefois, le recoupement de données ALB et ENC fournit une méthode additionnelle pour les régions comprenant d’importants chevauchements. La comparaison d’ENC s’avère utile à des endroits où il n’existe pas de données SMF et pour l’évaluation de l’exactitude de la carte

Infrared dust emission in the outer disk of M51

We examine faint infrared emission features detected in Spitzer Space Telescope images of M51, which are associated with atomic hydrogen in the outer disk and tidal tail at R greater than R_25 (4.9', ~14 kpc at d=9.6 Mpc). The infrared colors of these features are consistent with the colors of dust associated with star formation in the bright disk. However, the star formation efficiency (as a ratio of star formation rate to neutral gas mass) implied in the outer disk is lower than that in the bright disk of M51 by an order of magnitude, assuming a similar relationship between infrared emission and star formation rate in the inner and outer disks.Comment: 13 pages in manuscript form, 2 figures; download PDF of manuscript with original-resolution Figure 1 at http://www.eg.bucknell.edu/physics/thornley/thornleym51.pd

A New Family of Planets ? "Ocean Planets"

A new family of planets is considered which is between rochy terrestrial planets and gaseous giant ones: "Ocean-Planets". We present the possible formation, composition and internal models of these putative planets, including that of their ocean, as well as their possible Exobiology interest. These planets should be detectable by planet detection missions such as Eddington and Kepler, and possibly COROT (lauch scheduled in 2006). They would be ideal targets for spectroscopic missions such as Darwin/TPF.Comment: 15 pages, 3 figures submitted to Icarus notes (10 july 2003

The Ursinus Weekly, December 3, 1956

Nineteenth Messiah to be presented on Thurs. Dec. 6 • Two Ursinus grads die in accidents • Calendar meeting for Spring term held November 20 • UC Forum hears noted Japanese professor of law • UC professors attend registrars confab • Coombe - Rosser engagement • Men\u27s council issues warning on dress for meals • Class of \u2759 to give Dogpatch drag Sat. • Doll exhibit in Library • Help Hungary totals $182.57; Drive to continue until Dec. 14 • Seniors\u27 permanent officers announced at High society • Y meeting hears H.B. Hester speak • Phila. Orch. program will feature Gueden • Stars and Players plan programs; Accept members • Editorial: Help Hungary : Quality and quantity • Letters to the editor • Book review: Reason why • Story of the Messiah • Movie review: Friendly persuasion • Famous to captain \u2757 Bears; Donnelly takes MVP award • Belles boast five vets; Open Feb. 18 • Woodbury elected \u2757 hockey captain • Wrestling to begin on January 12th • Intramurals begin • Burger, Taylor and Chern to lead Yost\u27s cagers in 1957 • Bruin five fail to stop Prins; Drop home court opener to Aggie, 59-50 • J.V.s take victory • Alpha Psi takes in new group member • Pre-meds hear Carfagno; To meet with chem. soc. • McClures to give party for Jr. and Sr. women • Cross - Hummel engagement • Armstrongs have dinner • Christmas Communion service • Post Office appeals for early Christmas mailing • Duryea has Christmas party • Joan Finney addresses Canterbury meeting • Ursinus student\u27s poem to be publishedhttps://digitalcommons.ursinus.edu/weekly/1417/thumbnail.jp

The Ursinus Weekly, April 8, 1957

Co-editors choose staffs, make plans for 1958 Ruby • Dr. Staiger given grant to attend chemistry meeting • Curtain Club to present two plays • Pre-medders make visit to psychiatric hospital • U.C. April Forum to hear address on Egypt, Wed. eve. • Dead Sea scrolls to be Chi Alpha program topic • Annual Spring prom to be presented Friday, April 12th • Program to be held on various fields of social welfare • New Weekly editor-in-chief chooses staff editors, members • Seniors present Two-timer musical comedy, Fri. & Sat. • YW-YMCA present last song program • May Day court, committees chosen • Sig Nu, Delta Pi plan bake sale, orphans\u27 party • UC senior married March 23 • UC grad assigned to new post • Pancoast speaks at Thiel • Editorial: And they said they couldn\u27t do it • Ach, ist Fruhling • Lantern review • Play review: Two timer • Modern fairy tale • Meistersingers give concert • Inter-fraternity field, track events scheduled for Tuesday, April 9th • Sowers high in free throw • Belles complete successful season • Belles beginning tennis practice • U.C. mermaids complete season; Finish with two wins, three losses • Five members of U.C. Band attend annual festivalhttps://digitalcommons.ursinus.edu/weekly/1425/thumbnail.jp

IRAC Excess in Distant Star-Forming Galaxies: Tentative Evidence for the 3.3μ\mum Polycyclic Aromatic Hydrocarbon Feature ?

We present evidence for the existence of an IRAC excess in the spectral energy distribution (SED) of 5 galaxies at 0.6<z<0.9 and 1 galaxy at z=1.7. These 6 galaxies, located in the Great Observatories Origins Deep Survey field (GOODS-N), are star forming since they present strong 6.2, 7.7, and 11.3 um polycyclic aromatic hydrocarbon (PAH) lines in their Spitzer IRS mid-infrared spectra. We use a library of templates computed with PEGASE.2 to fit their multiwavelength photometry and derive their stellar continuum. Subtraction of the stellar continuum enables us to detect in 5 galaxies a significant excess in the IRAC band pass where the 3.3 um PAH is expected. We then assess if the physical origin of the IRAC excess is due to an obscured active galactic nucleus (AGN) or warm dust emission. For one galaxy evidence of an obscured AGN is found, while the remaining four do not exhibit any significant AGN activity. Possible contamination by warm dust continuum of unknown origin as found in the Galactic diffuse emission is discussed. The properties of such a continuum would have to be different from the local Universe to explain the measured IRAC excess, but we cannot definitively rule out this possibility until its origin is understood. Assuming that the IRAC excess is dominated by the 3.3 um PAH feature, we find good agreement with the observed 11.3 um PAH line flux arising from the same C-H bending and stretching modes, consistent with model expectations. Finally, the IRAC excess appears to be correlated with the star-formation rate in the galaxies. Hence it could provide a powerful diagnostic for measuring dusty star formation in z>3 galaxies once the mid-infrared spectroscopic capabilities of the James Webb Space Telescope become available.Comment: 25 pages, 4 figures, accepted by Ap