The Size Distribution of Trans-Neptunian Bodies

[Condensed] We search 0.02 deg^2 for trans-Neptunian objects (TNOs) with m<=29.2 (diameter ~15 km) using the ACS on HST. Three new objects are discovered, roughly 25 times fewer than expected from extrapolation of the differential sky density Sigma(m) of brighter objects. The ACS and other recent TNO surveys show departures from a power law size distribution. Division of the TNO sample into ``classical Kuiper belt'' (CKB) and ``Excited'' samples reveals that Sigma(m) differs for the two populations at 96% confidence. A double power law adequately fits all data. Implications include: The total mass of the CKB is ~0.010 M_Earth, only a few times Pluto's mass, and is predominately in the form of ~100 km bodies. The mass of Excited objects is perhaps a few times larger. The Excited class has a shallower bright-end size distribution; the largest objects, including Pluto, comprise tens of percent of the total mass whereas the largest CKBOs are only ~2% of its mass. The predicted mass of the largest Excited body is close to the Pluto mass; the largest CKBO is ~60 times less massive. The deficit of small TNOs occurs for sizes subject to disruption by present-day collisions, suggesting extensive depletion by collisions. Both accretion and erosion appearing to have proceeded to more advanced stages in the Excited class than the CKB. The absence of distant TNOs implies that any distant (60 AU) population must have less than the CKB mass in the form of objects 40 km or larger. The CKB population is sparser than theoretical estimates of the required precursor population for short period comets, but the Excited population could be a viable precursor population.Comment: Revised version accepted to the Astronomical Journal. Numerical results are very slightly revised. Implications for the origins of short-period comets are substantially revised, and tedious material on statistical tests has been collected into a new Appendi

Corrigendum: hypoxic induced decrease in oxygen consumption in cuttlefish (Sepia officinalis) Is Associated with minor increases in Mantle Octopine but no changes in markers of protein turnover

Corrige o artigo http://hdl.handle.net/10400.1/10858 [This corrects the article DOI: 10.3389/fphys.2017.00344.].info:eu-repo/semantics/publishedVersio

Guiding chemical pulses through geometry: Y-junctions

We study computationally and experimentally the propagation of chemical pulses in complex geometries.The reaction of interest, CO oxidation, takes place on single crystal Pt(110) surfaces that are microlithographically patterned; they are also addressable through a focused laser beam, manipulated through galvanometer mirrors, capable of locally altering the crystal temperature and thus affecting pulse propagation. We focus on sudden changes in the domain shape (corners in a Y-junction geometry) that can affect the pulse dynamics; we also show how brief, localized temperature perturbations can be used to control reactive pulse propagation.The computational results are corroborated through experimental studies in which the pulses are visualized using Reflection Anisotropy Microscopy.Comment: submitted to Phys. Rev.

A Variable Dispersion Flow Injection Manifold for Calibration and Sample Dilution in Flame Atomic Absorption Spectrometry

A flow injection (FI) introduction system for flame atomic absorption spectrometry (FAAS) has been constructed for single-standard calibration and sample dilution. Dilution factors ranging from 5.93 to 38.8 in six discrete stages were produced by replicate injection of 12.5-pl volumes into an aqueous carrier stream flowing down lines of different lengths. The dilution factors were measured for five different solutions for each line. No dependence on concentration was found and the relative standard deviations ranged from 0.75 to 3.1%. The manifold was evaluated by the analysis of solutions of magnesium (6,12.5 and 35 p.p.m.), nickel (180 p.p.m.), calcium (75 p.p.m.) and chromium (180 p.p.m.). Recoveries ranging from 95.3 to 106.8% were obtained with no over-all evidence of bias. The uncertainty in the over-all method, including a contribution from the curve-fitting procedure, was estimated to be 5%

Classification of image distortions in terms of Petrov types

An observer surrounded by sufficiently small spherical light sources at a fixed distance will see a pattern of elliptical images distributed over the sky, owing to the distortion effect (shearing effect) of the spacetime geometry upon light bundles. In lowest non-trivial order with respect to the distance, this pattern is completely determined by the conformal curvature tensor (Weyl tensor) at the observation event. In this paper we derive formulas that allow to calculate these distortion patterns in terms of the Newman-Penrose formalism. Then we represent the distortion patterns graphically for all Petrov types, and we discuss their dependence on the velocity of the observer.Comment: 22 pages, 8 eps-figures; revised version, parts of Introduction and Conclusions rewritte