4,921 research outputs found
The ontology of causal process theories
There is a widespread belief that the so-called process theories of causation developed by Wesley Salmon and Phil Dowe have given us an original account of what causation really is. In this paper, I show that this is a misconception. The notion of "causal process" does not offer us a new ontological account of causation. I make this argument by explicating the implicit ontological commitments in Salmon and Dowe's theories. From this, it is clear that Salmon's Mark Transmission Theory collapses to a counterfactual theory of causation, while the Conserved Quantity Theory collapses to David Fair's phsyicalist reduction of causation
Theurapeutic Effectiveness of Rat Bone Marrow Stem Cells in Poly Cystic Ovary Syndrome Mice Model on Folliculogenesis, TGF-β, GDF-9 Expression, and Estrogen, TNF- and Androgen Levels
Objectives: to identify therapeutic effectiveness of Rat Bone Marrow stem cell in PCOS rats model on folliculogenesis, TGF-beta and GDF-9 expression and on estrogen, TNF-a and androgen levels.Material and Methods: this study is a laboratory experimental research with using animal testing. PCOS was induced by the administration of testosterone propionate hormone into 30 mice. The subjects of this study are divided into 2 groups: stem cell group and control group. The mice were injected with testosterone then vaginal swab was performed to determine the mice cycle. After determining mice in anestrous cycle, stem cell was injected. TNF-a was measured with immunohistochemistry and androgen was examined using ELISA. The data was measured by student t-test.Result: The average number of TNF-a expression in control group was lower than stem cell group (5.35 vs 2.34; p= 0.0026). The average androgen level for stem cell group was lower than mean for control group (2.31 vs 0.40; p= 0.0026).Conclusion: In this study of polycystic model mice, stem cell decreased the expression of TNF-a and androgen leve
Visualizing elements of Sha[3] in genus 2 jacobians
Mazur proved that any element xi of order three in the Shafarevich-Tate group
of an elliptic curve E over a number field k can be made visible in an abelian
surface A in the sense that xi lies in the kernel of the natural homomorphism
between the cohomology groups H^1(k,E) -> H^1(k,A). However, the abelian
surface in Mazur's construction is almost never a jacobian of a genus 2 curve.
In this paper we show that any element of order three in the Shafarevich-Tate
group of an elliptic curve over a number field can be visualized in the
jacobians of a genus 2 curve. Moreover, we describe how to get explicit models
of the genus 2 curves involved.Comment: 12 page
Surface compositional mapping by spectral ratioing of ERTS-1 MSS data in the Wind River Basin and Range, Wyoming
The author has identified the following significant results. ERTS data collected in August and October 1972 were processed on digital and special purpose analog recognition computers using ratio enhancement and pattern recognition. Ratios of band-averaged laboratory reflectances of some minerals and rock types known to be in the scene compared favorably with ratios derived from the data by ratio normalization procedures. A single ratio display and density slice of the visible channels of ERTS MSS data, Channel 5/Channel 4 (R5,4), separated the Triassic Chugwater formation (redbeds) from other formations present and may have enhanced iron oxide minerals present at the surface in abundance. Comparison of data sets collected over the same area at two different times of the year by digital processing indicated that spectral variation due to environmental factors was reduced by ratio processing
Velocity Profiles in Slowly Sheared Bubble Rafts
Measurements of average velocity profiles in a bubble raft subjected to slow,
steady-shear demonstrate the coexistence between a flowing state and a jammed
state similar to that observed for three-dimensional foams and emulsions
[Coussot {\it et al,}, Phys. Rev. Lett. {\bf 88}, 218301 (2002)]. For
sufficiently slow shear, the flow is generated by nonlinear topological
rearrangements. We report on the connection between this short-time motion of
the bubbles and the long-time averages. We find that velocity profiles for
individual rearrangement events fluctuate, but a smooth, average velocity is
reached after averaging over only a relatively few events.Comment: typos corrected, figures revised for clarit
Shear-banding in a lyotropic lamellar phase, Part 2: Temporal fluctuations
We analyze the temporal fluctuations of the flow field associated to a
shear-induced transition in a lyotropic lamellar phase: the layering transition
of the onion texture. In the first part of this work [Salmon et al., submitted
to Phys. Rev. E], we have evidenced banded flows at the onset of this
shear-induced transition which are well accounted for by the classical picture
of shear-banding. In the present paper, we focus on the temporal fluctuations
of the flow field recorded in the coexistence domain. These striking dynamics
are very slow (100--1000s) and cannot be due to external mechanical noise.
Using velocimetry coupled to structural measurements, we show that these
fluctuations are due to a motion of the interface separating the two
differently sheared bands. Such a motion seems to be governed by the
fluctuations of , the local stress at the interface between the
two bands. Our results thus provide more evidence for the relevance of the
classical mechanical approach of shear-banding even if the mechanism leading to
the fluctuations of remains unclear
Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles
Using velocity profile measurements based on dynamic light scattering and
coupled to structural and rheological measurements in a Couette cell, we
present evidences for a shear-banding scenario in the shear flow of the onion
texture of a lyotropic lamellar phase. Time-averaged measurements clearly show
the presence of structural shear-banding in the vicinity of a shear-induced
transition, associated to the nucleation and growth of a highly sheared band in
the flow. Our experiments also reveal the presence of slip at the walls of the
Couette cell. Using a simple mechanical approach, we demonstrate that our data
confirms the classical assumption of the shear-banding picture, in which the
interface between bands lies at a given stress . We also outline
the presence of large temporal fluctuations of the flow field, which are the
subject of the second part of this paper [Salmon {\it et al.}, submitted to
Phys. Rev. E]
The bright-end galaxy candidates at z ~ 9 from 79 independent HST fields
We present a full data analysis of the pure-parallel Hubble Space Telescope
(HST) imaging observations in the Brightest of Reionizing Galaxies Survey
(BoRG[z9]) in Cycle 22. The medium-deep exposures with five HST/WFC3IR+UVIS
filter bands from 79 independent sightlines (~370 arcmin^2) provide the least
biased determination of number density for z>9 bright galaxies against cosmic
variance. After a strict two-step selection for candidate galaxies, including
dropout color and photometric redshift analyses, and revision of previous BoRG
candidates, we identify one source at z~10 and two sources at z~9. The z~10
candidate shows evidence of line-of-sight lens magnification (mu~1.5), yet it
appears surprisingly luminous (MUV ~ -22.6\pm0.3 mag), making it one of the
brightest candidates at z > 8 known (~ 0.3 mag brighter than the z = 8.68
galaxy EGSY8p7, spectroscopically confirmed by Zitrin and collaborators). For z
~ 9 candidates, we include previous data points at fainter magnitudes and find
that the data are well fitted by a Schechter luminosity function with alpha ~
-2.1, MUV ~ -21.5 mag, and log phi ~ -4.5 Mpc^-3mag^-1, for the first time
without fixing any parameters. The inferred cosmic star formation rate density
is consistent with unaccelerated evolution from lower redshift.Comment: 18pages, 7figures, 6tables. accepted to the Astrophysical Journa
Final report of the Committee on Depreciation; Dissenting opinion to the final report of the Committee on Depreciation
Losses of value which are complete, and fully demonstrated by proper abandonment or necessary replacement of the whole or a unit part of a property, are a matter of history and fact, and require only proper accounting to determine their occurrence and amount. Losses of value, which are partial or incomplete, always require prophecy as to future need, usefulness, and service, in order to properly divide that portion of the value which still exists from that which is lost. This function necessitates much more judgment than accounting. It requires the careful analysis of a broadly trained, experienced, and practical mind, thoroughly familiar with the business in question. Original item in Boxno. 0409
Discussing ethical issues in school science: An investigation into the opportunities to practise and develop arguments offered by online and face-to-face discussions
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