758 research outputs found
Chemistry of Diogenites and Evolution of their Parent Asteroid
Diogenites are orthopyroxenite meteorites [1]. Most are breccias, but remnant textures indicate they were originally coarse-grained rocks, with grain sizes of order of cm. Their petrography, and major and trace element chemistry support an origin as crustal cumulates from a differentiated asteroid. Diogenites are genetically related to the basaltic and cumulate-gabbro eucrites, and the polymict breccias known as howardites, collectively, the HED suite. Spectroscopic observations, orbit data and dynamical arguments strongly support the hypothesis that asteroid 4 Vesta is the parent object for HED meteorites [2]. Here we discuss our new trace element data for a suite of diogenites and integrate these into the body of literature data. We use the combined data set to discuss the petrologic evolution of diogenites and 4 Vesta
Systematic effects in the extraction of the 'WMAP haze'
The extraction of a 'haze' from the WMAP microwave skymaps is based on
subtraction of known foregrounds, viz. free-free (bremsstrahlung), thermal dust
and synchrotron, each traced by other skymaps. While the 408 MHz all-sky survey
is used for the synchrotron template, the WMAP bands are at tens of GHz where
the spatial distribution of the radiating cosmic ray electrons ought to be
quite different because of the energy-dependence of their diffusion in the
Galaxy. The systematic uncertainty this introduces in the residual skymap is
comparable to the claimed haze and can, for certain source distributions, have
a very similar spectrum and latitudinal profile and even a somewhat similar
morphology. Hence caution must be exercised in interpreting the 'haze' as a
physical signature of, e.g., dark matter annihilation in the Galactic centre.Comment: 17 pages, 12 figures; improved diffusion model; extended discussion
of spectral index maps; clarifying comments, figures and references added; to
appear in JCA
Sociology Back to the Publics
This article is a reading of the `new sociology' that is mainly identified with the works of C. Wright Mills and Alvin Gouldner. Its main argument is that during the past 40 years the new sociology gave back a public face to sociology. This distinguishes it from the `old sociology' that had not been able to free itself from `private' social values. It is argued that Mills' power elite and Gouldner's coming crisis theses provided the foundation for a common enterprise among many `new sociologists' to develop a critical and public sociology that would seek to shape what Mills called the `democratic society of publics'.`New sociologists' share a critique of modern societies, namely, that though most modern societies have formal democracies, a substantial democratic social structure of publics is often lacking, due to the erosion of the public sphere by private values
Magnetic Fields in the Milky Way
This chapter presents a review of observational studies to determine the
magnetic field in the Milky Way, both in the disk and in the halo, focused on
recent developments and on magnetic fields in the diffuse interstellar medium.
I discuss some terminology which is confusingly or inconsistently used and try
to summarize current status of our knowledge on magnetic field configurations
and strengths in the Milky Way. Although many open questions still exist, more
and more conclusions can be drawn on the large-scale and small-scale components
of the Galactic magnetic field. The chapter is concluded with a brief outlook
to observational projects in the near future.Comment: 22 pages, 5 figures, to appear in "Magnetic Fields in Diffuse Media",
eds. E.M. de Gouveia Dal Pino and A. Lazaria
Neutron Structure Function and A=3 Mirror Nuclei
We investigate deep inelastic scattering from He-3 and H-3 within a
conventional convolution treatment of binding and Fermi motion effects. Using
realistic Faddeev wave functions together with a nucleon spectral function, we
demonstrate that the free neutron structure function can be extracted in
deep-inelastic scattering from A=3 mirror nuclei, with nuclear effects
canceling to within 2% for x < 0.85.Comment: 13 pages, 4 figures, version to appear in Phys. Lett.
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles
In the G0 experiment, performed at Jefferson Lab, the parity-violating
elastic scattering of electrons from protons and quasi-elastic scattering from
deuterons is measured in order to determine the neutral weak currents of the
nucleon. Asymmetries as small as 1 part per million in the scattering of a
polarized electron beam are determined using a dedicated apparatus. It consists
of specialized beam-monitoring and control systems, a cryogenic hydrogen (or
deuterium) target, and a superconducting, toroidal magnetic spectrometer
equipped with plastic scintillation and aerogel Cerenkov detectors, as well as
fast readout electronics for the measurement of individual events. The overall
design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method
Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
We have measured the beam-normal single-spin asymmetry in elastic scattering
of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 =
0.15, 0.25 (GeV/c)^2. The results are inconsistent with calculations solely
using the elastic nucleon intermediate state, and generally agree with
calculations with significant inelastic hadronic intermediate state
contributions. A_n provides a direct probe of the imaginary component of the
2-gamma exchange amplitude, the complete description of which is important in
the interpretation of data from precision electron-scattering experiments.Comment: 5 pages, 3 figures, submitted to Physical Review Letters; shortened
to meet PRL length limit, clarified some text after referee's comment
Strange Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment
We have measured parity-violating asymmetries in elastic electron-proton
scattering over the range of momentum transfers 0.12 < Q^2 < 1.0 GeV^2. These
asymmetries, arising from interference of the electromagnetic and neutral weak
interactions, are sensitive to strange quark contributions to the currents of
the proton. The measurements were made at JLab using a toroidal spectrometer to
detect the recoiling protons from a liquid hydrogen target. The results
indicate non-zero, Q^2 dependent, strange quark contributions and provide new
information beyond that obtained in previous experiments.Comment: 5 pages, 2 figure
Codes of Fair Competition: The National Recovery Act, 1933-1935, and the Women’s Dress Manufacturing Industry
Controversial issues prevalent in today’s ready-to-wear apparel industry include the right of workers to join unions, the proliferation of sweatshops and sweatshop conditions, and design piracy. The idea of forming codes of conduct to establish criteria of ethical business practices is not new to the apparel industry. Indeed, the women’s dress manufacturing industry discussed and debated codes of fair competition under the New Deal Policies of the National Recovery Act (NRA) of 1933 to 1935. Primary sources for this study included governmental hearings in the establishment of the NRA Dress Code, The New York Times, Women’s Wear Daily, and the Journal of the Patent Office Society. The history of the NRA codes implemented in the U.S. women’s ready-to-wear apparel industry provides an important case study highlighting the difficulties and complexities of creating and achieving industry-wide standard practices through self-regulation. The failure of the NRA demonstrates that even with the joint cooperation of industry, labor, and consumer groups and the backing of the force of law, codes of fair competition proved impossible to enforce
Strangeness in the Nucleon on the Light-Cone
Strange matrix elements of the nucleon are calculated within the light-cone
formulation of the meson cloud model. The dependence of the strange
vector and axial vector form factors is computed, and the strangeness radius
and magnetic moment extracted, both of which are found to be very small and
slightly negative. Within the same framework one finds a small but non-zero
excess of the antistrange distribution over the strange at large . Kaon
loops are unlikely, however, to be the source of a large polarized strange
quark distribution.Comment: 22 pages revtex, 7 postscript figures, accepted for publication in
Phys. Rev.
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