784 research outputs found
THE POWER OF STRUCTURED DESIGNS AND MIXED MODELS IN A REAL WORLD EXPERIMENT
Justifications usually given for adopting an automated system pertain to a reduction in labor and an improvement in quality control. A manufacturer of a prototype instrument that automated some of the steps for culturing bacteria wanted to compare the automated system to the manual system. The manufacturer wanted to compare the two systems in 1) Total time needed to isolate the target bacteria, 2) Ability to isolate the target bacteria, 3) Amount of interference from background (non-target) bacterial growth, and 1) Extent of cross (sample to sample) contamination.
This paper presents the experimental design used to make these comparisons and how the design helped discover some surprising results about laboratory quality control. The experiment presented illustrates the importance of a good experimental design, the power of current statistical tools, and that a thorough and appropriate analysis of a data set requires side-by-side good detective work by both statistician and client
Environmental Asbestotic Pleural Plaques in Northeast Corsica: Correlations with Airborne and Pleural Mineralogic Analysis
We report a prevalence study of environmental pleural plaques in subjects over 50 years old from the northeastern Corsican village of Murato, built on asbestos surface deposits. The percentage of plaques was 41%, versus 7.5% in the control village of Vezzani. Although surface deposits contain both chrysotile and tremolite, airborne pollution and asbestos lung burden of exposed inhabitants consist essentially of tremolite as assessed by transmission electron microscopy (TEM). However, TEM analysis of the parietal pleura of three animals bred in exposed areas showed a predominance of short fibers of chrysotile. The respective roles of tremolite and chrysotile in inducing pleural plaques in Corsica should thus be considered.—Environ Health Perspect 102(Suppl 5):251–252 (1994
Elodie metallicity-biased search for transiting Hot Jupiters IV. Intermediate period planets orbiting the stars HD43691 and HD132406
We report here the discovery of two planet candidates as a result of our
planet-search programme biased in favour of high-metallicity stars, using the
ELODIE spectrograph at the Observatoire de Haute Provence. One of them has a
minimum mass m_2\sin{i} = 2.5 M_Jup and is orbiting the metal-rich star HD43691
with period P = 40 days and eccentricity e = 0.14. The other planet has a
minimum mass m_2\sin{i} = 5.6 M_Jup and orbits the slightly metal-rich star
HD132406 with period P = 974 days and eccentricity e = 0.34. Both stars were
followed up with additional observations using the new SOPHIE spectrograph that
replaces the ELODIE instrument, allowing an improved orbital solution for the
systems.Comment: 6 pages, 4 figures, to be published in A&
Refined parameters and spectroscopic transit of the super-massive planet HD147506b
In this paper, we report a refined determination of the orbital parameters
and the detection of the Rossiter-McLaughlin effect of the recently discovered
transiting exoplanet HD147506b (HAT-P-2b). The large orbital eccentricity at
the short orbital period of this exoplanet is unexpected and is distinguishing
from other known transiting exoplanets. We performed high-precision radial
velocity spectroscopic observations of HD147506 (HAT-P-2) with the new
spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence
observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and
20 on June 11, when the planet was transiting its parent star. The radial
velocity (RV) anomaly observed illustrates that HAT-P-2b orbital motion is set
in the same direction as its parent star spin. The sky-projected angle between
the normal of the orbital plane and the stellar spin axis, \lambda = 0.2 +12.2
-12.5 deg, is consistent with zero. The planetary and stellar radii were
re-determined, yielding R_p = 0.951 +0.039 -0.053 R_Jup, R_s = 1.416 +0.040
-0.062 R_Sun. The mass M_p = 8.62 +0.39 -0.55 M_Jup and radius of HAT-P-2b
indicate a density of 12.5 +2.6 -3.6 g cm^{-3}, suggesting an object in between
the known close-in planets with typical density of the order of 1 g cm^{-3},
and the very low-mass stars, with density greater than 50 g cm^{-3}.Comment: Submitted to A&A; V2: Replaced by accepted versio
Impact of permeability evolution in igneous sills on hydrothermal flow and hydrocarbon transport in volcanic sedimentary basins
Sills emplaced in organic-rich sedimentary rocks trigger the generation and
migration of hydrocarbons in volcanic sedimentary basins. Based on seismic
and geological observations, numerical modeling studies of hydrothermal flow
around sills show that thermogenic methane is channeled below the intrusion
towards its tip, where hydrothermal vents nucleate and transport methane to
the surface. However, these models typically assume impermeable sills and
ignore potential effects of permeability evolution in cooling sills, e.g.,
due to fracturing. Here, we combine a geological field study of a volcanic
basin (Neuquén Basin, Argentina) with a hybrid finite-element–finite-volume method (FEM–FVM) of numerical modeling
of hydrothermal flow around a sill, including hydrocarbon generation and
transport. Our field observations show widespread veins within sills
composed of graphitized bitumen and cooling joints filled with solid bitumen
or fluidized shale. Raman spectroscopy indicates graphitization at
temperatures between 350 and 500 ∘C, suggesting fluid flow within the
intrusions during cooling. This finding motivates our modeling setup, which
investigates flow patterns around and through intrusions that become porous
and permeable upon solidification. The results show three flow phases
affecting the transport of hydrocarbons generated in the contact aureole:
(1) contact-parallel flow toward the sill tip prior to solidification, (2)
upon complete solidification, sudden vertical “flushing” of overpressured
hydrocarbon-rich fluids from the lower contact aureole towards and into the
hot sill along its entire length, and (3) stabilization of hydrocarbon
distribution and fading hydrothermal flow. In low-permeability host rocks,
hydraulic fracturing facilitates flow and hydrocarbon migration toward the
sill by temporarily elevating porosity and permeability. Up to 7.5 % of
the generated methane is exposed to temperatures >400 ∘C in the simulations and may thus be permanently stored as graphite in or
near the sill. Porosity and permeability creation within cooling sills may
impact hydrothermal flow, hydrocarbon transport, and venting in volcanic
basins, as it considerably alters the fluid pressure configuration, provides
vertical flow paths, and helps to dissipate overpressure below the sills.</p
Search for brown-dwarf companions of stars
The discovery of 9 new brown-dwarf candidates orbiting stars in the CORALIE
and HARPS radial-velocity surveys is reported. New CORALIE radial velocities
yielding accurate orbits of 6 previously-known hosts of potential brown-dwarf
companions are presented. Including targets selected from the literature, 33
hosts of potential brown-dwarf companions are examined. Employing innovative
methods, we use the new reduction of the Hipparcos data to fully characterise
the astrometric orbits of 6 objects, revealing M-dwarf companions with masses
between 90 M_Jup and 0.52 M_Sun. Additionally, the masses of two companions can
be restricted to the stellar domain. The companion to HD 137510 is found to be
a brown dwarf. At 95 % confidence, the companion of HD 190228 is also a brown
dwarf. The remaining 23 companions persist as brown-dwarf candidates. Based on
the CORALIE planet-search sample, we obtain an upper limit of 0.6 % for the
frequency of brown-dwarf companions around Sun-like stars. We find that the
companion-mass distribution function is rising at the lower end of the
brown-dwarf mass range, suggesting that in fact we are detecting the high-mass
tail of the planetary distribution.Comment: 24 pages, 21 figures, 10 tables. Accepted for publication in
Astronomy and Astrophysics. Abridged abstrac
Magnetism, FeS colloids, and Origins of Life
A number of features of living systems: reversible interactions and weak
bonds underlying motor-dynamics; gel-sol transitions; cellular connected
fractal organization; asymmetry in interactions and organization; quantum
coherent phenomena; to name some, can have a natural accounting via
interactions, which we therefore seek to incorporate by expanding the horizons
of `chemistry-only' approaches to the origins of life. It is suggested that the
magnetic 'face' of the minerals from the inorganic world, recognized to have
played a pivotal role in initiating Life, may throw light on some of these
issues. A magnetic environment in the form of rocks in the Hadean Ocean could
have enabled the accretion and therefore an ordered confinement of
super-paramagnetic colloids within a structured phase. A moderate H-field can
help magnetic nano-particles to not only overcome thermal fluctuations but also
harness them. Such controlled dynamics brings in the possibility of accessing
quantum effects, which together with frustrations in magnetic ordering and
hysteresis (a natural mechanism for a primitive memory) could throw light on
the birth of biological information which, as Abel argues, requires a
combination of order and complexity. This scenario gains strength from
observations of scale-free framboidal forms of the greigite mineral, with a
magnetic basis of assembly. And greigite's metabolic potential plays a key role
in the mound scenario of Russell and coworkers-an expansion of which is
suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed
Krishnaswami Alladi, Springer 201
VLT/NACO coronagraphic observations of fine structures in the disk of beta Pictoris
We present ground-based observations of the disk around the A-type star
Pictoris to perform a close inspection of the inner disk morphology.
Images were collected with NACO, the AO-assisted near-IR instrument on the VLT
(ESO) which includes two types of coronagraphs: classical Lyot masks and phase
masks. In this program we took advantage of both types of coronagraphs in two
spectral bands, H-band for the Lyot mask and Ks-band for the phase mask. In
addition, we simulated an extended object to understand the limitations in
deconvolution of coronagraphic images. The reduced coronagraphic images allow
us to carefully measure the structures of the debris disk and reveal a number
of asymmetries of which some were not reported before (position, elevation and
thickness of the warp). In this program, the circumstellar material is visible
as close as 0.7" (AU) owing to the phase mask while the Lyot mask
generates artifacts which hamper the detection of the dust at separations
closer than 1.2" (AU). The point source detection limit is compared to
recently published observations of a planet candidate. Finally, the simulations
show that deconvolution of coronagraphic data may indeed produce artificial
patterns within the image of a disk.Comment: 13 pages, to appear in Astronomy and Astrophysic
Pixel-wise segmentation of SAR imagery using encoder-decoder network and fully-connected CRF
Synthetic Aperture Radar (SAR) image segmentation is an important step in SAR image interpretation. Common Patch-based methods treat all the pixels within the patch as a single category and do not take the label consistency between neighbor patches into consideration, which makes the segmentation results less accurate. In this paper, we use an encoder-decoder network to conduct pixel-wise segmentation. Then, in order to make full use of the contextual information between patches, we use fully-connected conditional random field to optimize the combined probability map output from encoder-decoder network. The testing results on our SAR data set shows that our method can effectively maintain contextual information of pixels and achieve better segmentation results
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