759 research outputs found
LOGICAL ANALYSIS AND LATER MOHIST LOGIC: SOME COMPARATIVE REFLECTIONS [abstract]
Any philosophical method that treats the analysis of the meaning of a sentence or expression in terms of a decomposition into a set of conceptually basic constituent parts must do some theoretical work to explain the puzzles of intensionality. This is because intensional phenomena appear to violate the principle of compositionality, and the assumption of compositionality is the principal justification for thinking that an analysis will reveal the real semantical import of a sentence or expression through a method of decomposition. Accordingly, a natural strategy for dealing with intensionality is to argue that it is really just an isolable, aberrant class of linguistic phenomena that poses no general threat to the thesis that meaning is basically compositional. On the other hand, the later Mohists give us good reason to reject this view. What we learn from them is that there may be basic limitations in any analytical technique that presupposes that meaning is perspicuously represented only when it has been fully decomposed into its constituent parts. The purpose of this paper is to (a) explain why the Mohists found the issue of intensionality to be so important in their investigations of language, and (b) defend the view that Mohist insights reveal basic limitations in any technique of analysis that is uncritically applied with a decompositional approach in mind, as are those that are often pursued in the West in the context of more general epistemological and metaphysical programs
Deep imaging of Eridanus II and its lone star cluster
We present deep imaging of the most distant dwarf discovered by the Dark
Energy Survey, Eridanus II (Eri II). Our Magellan/Megacam stellar photometry
reaches mag deeper than previous work, and allows us to confirm the
presence of a stellar cluster whose position is consistent with Eri II's
center. This makes Eri II, at , the least luminous galaxy known to
host a (possibly central) cluster. The cluster is partially resolved, and at
it accounts for of Eri II's luminosity. We derive
updated structural parameters for Eri II, which has a half-light radius of
pc and is elongated (), at a measured
distance of kpc. The color-magnitude diagram displays a blue,
extended horizontal branch, as well as a less populated red horizontal branch.
A central concentration of stars brighter than the old main sequence turnoff
hints at a possible intermediate-age ( Gyr) population; alternatively,
these sources could be blue straggler stars. A deep Green Bank Telescope
observation of Eri II reveals no associated atomic gas.Comment: 7 pages, 4 figures; ApJL accepte
Antlia B: A faint dwarf galaxy member of the NGC 3109 association
We report the discovery of Antlia B, a faint dwarf galaxy at a projected
distance of 72 kpc from NGC 3109 (15 mag), the primary
galaxy of the NGC 3109 dwarf association at the edge of the Local Group. The
tip of the red giant branch distance to Antlia B is =1.290.10 Mpc,
which is consistent with the distance to NGC 3109. A qualitative analysis
indicates the new dwarf's stellar population has both an old, metal poor red
giant branch (10 Gyr, [Fe/H]2), and a younger blue population
with an age of 200-400 Myr, analogous to the original Antlia dwarf,
another likely satellite of NGC 3109. Antlia B has \ion{H}{1} gas at a velocity
of =376 km s, confirming the association with NGC 3109
(=403 km s). The HI gas mass
(M=2.80.210 M), stellar luminosity
(=9.70.6 mag) and half light radius (=27329 pc) are
all consistent with the properties of dwarf irregular and dwarf spheroidal
galaxies in the Local Volume, and is most similar to the Leo P dwarf galaxy.
The discovery of Antlia B is the initial result from a Dark Energy Camera
survey for halo substructure and faint dwarf companions to NGC 3109 with the
goal of comparing observed substructure with expectations from the
+Cold Dark Matter model in the sub-Milky Way regime.Comment: 7 pages, 3 figures. Submitted to ApJ
Multiplex analysis of heterophil antibodies in patients with indeterminate HIV immunoassay results
Journal ArticleWe hypothesized that heterophil antibodies reactive with animal proteins used in blot preparation caused nonspecific staining (NSS) on HIV Western blot (WB) studies, causing indeterminate results. We analyzed samples showing NSS on HIV WB using a multiplexed immunoassay to simultaneously measure IgG antibodies to animal IgG (bovine, goat, sheep, mouse) and bovine serum albumin. Heterophil antibodies reactive with IgG from several animal species were detected in 23 (49%) of 47 samples showing NSS on HIV WB; 15 positive samples demonstrated antibodies to all 5 antigens. Similar IgG heterophil antibodies were detected in only 2 (8%) of 24 control samples. Of the HIV WB samples with a positive HIV-1 enzymelinked immunosorbent assay (ELISA) result at the time of WB testing (11/47), heterophil antibodies were found in 8 (73%) of 11. Preabsorption with bovine, goat, and sheep IgG removed heterophil antibodies detected by the multiplexed assay and, in some cases, eliminated reactivity in ELISA and WB testing. Heterophil antibodies are associated with indeterminate HIV immunoassay results and are an important cause of false-positive HIV ELISA results. Multiplexed immunoassays provide a powerful tool for screening patients for heterophil antibodies and resolving possible false-positive results
Fluid Flow Velocity Measurement in Active Wells Using Using Fiber Optic Distributed Acoustic Sensors
Real time monitoring of the behaviour of fluids along the whole length of fluid filled well pipes is important to the oil and gas industry as it enables well operators to maximize oil and gas production and optimize the quality of oil and gas produced, whilst reducing the cost. Flow speed measurement is one of the key approaches in fluid flow monitoring in wells. In this paper, three methods are designed, developed and demonstrated to estimate the speed and direction of flow at a range of depths in real world oil, gas and water wells using acoustic data set from distributed acoustic sensors that attached to the wells. The developed methods are based on a new combination of several techniques from signal processing, machine learning and physics. The Terabyte size acoustic dataset are recorded from each well as a two-dimensional function of both distance along the pipeline and time. The aim of the developed methods is estimating flow speed at each point along over 3000 meters pipelines and increasing the accurately and efficiently of the flow speed calculation compared to the existing method. The methods developed in this paper are computationally inexpensive, which make them suitable for real time well monitoring
A Complete Spectroscopic Survey of the Milky Way satellite Segue 1: Dark matter content, stellar membership and binary properties from a Bayesian analysis
We introduce a comprehensive analysis of multi-epoch stellar line-of-sight
velocities to determine the intrinsic velocity dispersion of the ultrafaint
satellites of the Milky Way. Our method includes a simultaneous Bayesian
analysis of both membership probabilities and the contribution of binary
orbital motion to the observed velocity dispersion within a 14-parameter
likelihood. We apply our method to the Segue 1 dwarf galaxy and conclude that
Segue 1 is a dark-matter-dominated galaxy at high probability with an intrinsic
velocity dispersion of 3.7^{+1.4}_{-1.1} km/sec. The dark matter halo required
to produce this dispersion must have an average density of 2.5^{+4.1}_{-1.9}
solar mass/pc^3 within a sphere that encloses half the galaxy's stellar
luminosity. This is the highest measured density of dark matter in the Local
Group. Our results show that a significant fraction of the stars in Segue 1 may
be binaries with the most probable mean period close to 10 years, but also
consistent with the 180 year mean period seen in the solar vicinity at about 1
sigma. Despite this binary population, the possibility that Segue 1 is a bound
star cluster with the observed velocity dispersion arising from the orbital
motion of binary stars is disfavored by the multi-epoch stellar velocity data
at greater than 99% C.L. Finally, our treatment yields a projected
(two-dimensional) half-light radius for the stellar profile of Segue 1 of
28^{+5}_{-4} pc, in excellent agreement with photometric measurements.Comment: 15 pages, 19 figure
Willman 1 - a probable dwarf galaxy with an irregular kinematic distribution
We investigate the kinematic properties and stellar population of the
Galactic satellite Willman 1 (Wil 1) by combining Keck/DEIMOS spectroscopy with
KPNO mosaic camera imaging. Wil 1 is an ultra-low luminosity Milky Way
companion. This object lies in a region of size-luminosity space (M_V ~ -2 mag,
d ~ 38 kpc, r_half ~ 20 pc) also occupied by the Galactic satellites Bo\"otes
II and Segue 1 and 2, but no other known old stellar system. We use kinematic
and color-magnitude criteria to identify 45 stars as possible members of Wil 1.
With a systemic velocity of v_helio = -12.8 +/- 1.0 km/s, Wil 1 stars have
velocities similar to those of foreground Milky Way stars. Informed by
Monte-Carlo simulations, we identify 5 of the 45 candidate member stars as
likely foreground contaminants. We confirm a significant spread in the
abundances of the likely Wil 1 red giant branch members ([Fe/H] = -1.73 +/-
0.12 and -2.65 +/- 0.12, [Ca/Fe] = -0.4 +/- 0.18 and +0.13 +/- 0.28). This
spread supports the scenario that Wil 1 is an ultra-low luminosity dwarf galaxy
rather than a star cluster. Wil 1's innermost stars move with radial velocities
offset by 8 km/s from its outer stars and have a velocity dispersion consistent
with 0 km/s, suggesting that Wil 1 may not be in dynamical equilibrium. The
combination of the foreground contamination and unusual kinematic distribution
make it difficult to robustly determine the dark matter mass of Wil 1. As a
result, X-ray or gamma-ray observations of Wil 1 that attempt to constrain
models of particle dark matter using an equilibrium mass model are strongly
affected by the systematics in the observations presented here. We conclude
that, despite the unusual features in the Wil 1 kinematic distribution,
evidence indicates that this object is, or at least once was, a dwarf galaxy.Comment: AJ accepted version. The primary improvements are a detailed
investigation of the membership probability (Section 3.4 and new Figures 6, 7
and 8) and the revised spectroscopic [Fe/H] and [Ca/Fe] measurements of the
two brightest member stars. Conclusions are unchanged from the submitted
versio
- …