14,461 research outputs found
Saturn sa-9/pegasus a postflight trajectory
Postflight trajectory analysis and orbital flight discussion for Saturn I /SA- 9/ launch vehicle carrying Pegasus payloa
On hemispheric differences in evoked potentials to speech stimuli
Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks
Abundance, distribution, and habitat of leatherback turtles (Dermochelys coriacea) off California, 1990−2003
Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line-transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990−2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV] =0.75) in 1995 to 379 (CV= 0.23) in 1990, averaging 178 (CV= 0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle
Structural Performance of a Compressively Loaded Foam-Core Hat-Stiffened Textile Composite Panel
A structurally efficient hat-stiffened panel concept that utilizes a structural foam as a stiffener core material has been designed and developed for aircraft primary structural applications. This stiffener concept is fabricated from textile composite material forms with a resin transfer molding process. This foam-filled hat-stiffener concept is structurally more efficient than most other prismatically stiffened panel configurations in a load range that is typical for both fuselage and wing structures. The panel design is based on woven/stitched and braided graphite-fiber textile preforms, an epoxy resin system, and Rohacell foam core. The structural response of this panel design was evaluated for its buckling and postbuckling behavior with and without low-speed impact damage. The results from single-stiffener and multi-stiffener specimen tests suggest that this structural concept responds to loading as anticipated and has excellent damage tolerance characteristics compared to a similar panel design made from preimpregnated graphite-epoxy tape material
The connection between the host halo and the satellite galaxies of the Milky Way
Many properties of the Milky Way's dark matter halo, including its mass
assembly history, concentration, and subhalo population, remain poorly
constrained. We explore the connection between these properties of the Milky
Way and its satellite galaxy population, especially the implication of the
presence of the Magellanic Clouds for the properties of the Milky Way halo.
Using a suite of high-resolution -body simulations of Milky Way-mass halos
with a fixed final Mvir ~ 10^{12.1}Msun, we find that the presence of
Magellanic Cloud-like satellites strongly correlates with the assembly history,
concentration, and subhalo population of the host halo, such that Milky
Way-mass systems with Magellanic Clouds have lower concentration, more rapid
recent accretion, and more massive subhalos than typical halos of the same
mass. Using a flexible semi-analytic galaxy formation model that is tuned to
reproduce the stellar mass function of the classical dwarf galaxies of the
Milky Way with Markov-Chain Monte-Carlo, we show that adopting host halos with
different mass-assembly histories and concentrations can lead to different
best-fit models for galaxy-formation physics, especially for the strength of
feedback. These biases arise because the presence of the Magellanic Clouds
boosts the overall population of high-mass subhalos, thus requiring a different
stellar-mass-to-halo-mass ratio to match the data. These biases also lead to
significant differences in the mass--metallicity relation, the kinematics of
low-mass satellites, the number counts of small satellites associated with the
Magellanic Clouds, and the stellar mass of Milky Way itself. Observations of
these galaxy properties can thus provide useful constraints on the properties
of the Milky Way halo.Comment: 20 pages, 12 figures, accepted for publication in ApJ. A new section
on the effect of host halo mass-assembly history on the central galaxy
stellar mass is adde
A New Method for Calculating Arrival Distribution of Ultra-High Energy Cosmic Rays above 10^19 eV with Modifications by the Galactic Magnetic Field
We present a new method for calculating arrival distribution of UHECRs
including modifications by the galactic magnetic field. We perform numerical
simulations of UHE anti-protons, which are injected isotropically at the earth,
in the Galaxy and record the directions of velocities at the earth and outside
the Galaxy for all of the trajectories. We then select some of them so that the
resultant mapping of the velocity directions outside the Galaxy of the selected
trajectories corresponds to a given source location scenario, applying
Liouville's theorem. We also consider energy loss processes of UHE protons in
the intergalactic space. Applying this method to our source location scenario
which is adopted in our recent study and can explain the AGASA observation
above 4 \times 10^{19} eV, we calculate the arrival distribution of UHECRs
including lower energy (E>10^19 eV) ones. We find that our source model can
reproduce the large-scale isotropy and the small-scale anisotropy on UHECR
arrival distribution above 10^19 eV observed by the AGASA. We also demonstrate
the UHECR arrival distribution above 10^19 eV with the event number expected by
future experiments in the next few years. The interesting feature of the
resultant arrival distribution is the arrangement of the clustered events in
the order of their energies, reflecting the directions of the galactic magnetic
field. This is also pointed out by Alvarez-Muniz et al.(2002). This feature
will allow us to obtain some kind of information about the composition of
UHECRs and the magnetic field with increasing amount of data.Comment: 10 pages, 8 figures, to appear in the Astrophysical Journa
The Rachel Carson Letters and the Making of Silent Spring
Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
Chemical Composition of Ground Water and the Locations of Permeable Zones in the Yucca Mountain Area, Nevada
Ten wells in the Yucca Mountain area of southern Nevada have been sampled for chemical analysis. Samples were obtained during pumping of water from the entire well bore (composite sample) and in one instance by pumping water from a single isolated interval in well UE-25b#1. Sodium is the most abundant cation and bicarbonate the most abundant anion in all water samples. Although the general chemical compositions of individual samples are similar, there are significant differences in uncorrected carbon-14 age and in inorganic and stable-isotope composition. Flow surveys of seven wells performed using iodine-131 as a tracer indicate that ground-water production is usually from one or more discrete zones of permeability
- …