6,056 research outputs found
An annotated bibliography of propellant processing methods
The author has specialized in space resources research for many years, with special emphasis on oxygen reduction methods. He has been retained to write a comprehensive review of these methods, detailing advantages and disadvantages, listing by-products and presenting recommendations. As the first step, an extensive outline was prepared, and the portion of this outline covering product manufacture was selected as the initial goal. A working version is presented
Phonological similarity effects in Cantonese word recognition
Two lexical decision experiments in Cantonese are described in which the recognition of spoken target words as a function of phonological similarity to a preceding prime is investigated. Phonological similaritv in first syllables produced inhibition, while similarity in second syllables led to facilitation. Differences between syllables in tonal and segmental structure had generally similar effects
Compression of Martian atmosphere for production of oxygen
The compression of CO2 from the Martian atmosphere for production of O2 via an electrochemical cell is addressed. Design specifications call for an oxygen production rate of 10 kg per day and for compression of 50 times that mass of CO2. Those specifications require a compression rate of over 770 cfm at standard Martian temperature and pressure (SMTP). Much of the CO2 being compressed represents waste, unless it can be recycled. Recycling can reduce the volume of gas that must be compressed to 40 cfm at SMTP. That volume reduction represents significant mass savings in the compressor, heating equipment, filters, and energy source. Successful recycle of the gas requires separation of CO (produced in the electrochemical cell) from CO2, N2, and Ar found in the Martian atmosphere. That aspect was the focus of this work
Speakers differentiate English intrusive and onset /r/, but L2 listeners do not
We investigated whether non-native listeners can exploit phonetic detail in recognizing potentially ambiguous utterances, as native listeners can [6, 7, 8, 9, 10]. Due to the phenomenon of intrusive /r/, the English phrase extra ice may sound like extra rice. A production study indicates that the intrusive /r/ can be distinguished from the onset /r/ in rice, as it is phonetically weaker. In two cross-modal identity priming studies, however, we found no conclusive evidence that Dutch learners of English are able to make use of this difference. Instead, auditory primes such as extra rice and extra ice with onset and intrusive /r/s activate both types of targets such as ice and rice. This supports the notion of spurious lexical activation in L2 perception
Improved Stack-Slide Searches for Gravitational-Wave Pulsars
We formulate and optimize a computational search strategy for detecting
gravitational waves from isolated, previously-unknown neutron stars (that is,
neutron stars with unknown sky positions, spin frequencies, and spin-down
parameters). It is well known that fully coherent searches over the relevant
parameter-space volumes are not computationally feasible, and so more
computationally efficient methods are called for. The first step in this
direction was taken by Brady & Creighton (2000), who proposed and optimized a
two-stage, stack-slide search algorithm. We generalize and otherwise improve
upon the Brady-Creighton scheme in several ways. Like Brady & Creighton, we
consider a stack-slide scheme, but here with an arbitrary number of
semi-coherent stages and with a coherent follow-up stage at the end. We find
that searches with three semi-coherent stages are significantly more efficient
than two-stage searches (requiring about 2-5 times less computational power for
the same sensitivity) and are only slightly less efficient than searches with
four or more stages. We calculate the signal-to-noise ratio required for
detection, as a function of computing power and neutron star spin-down-age,
using our optimized searches.Comment: 19 pages, 7 figures, RevTeX
Recovering the stationary phase condition for accurately obtaining scattering and tunneling times
The stationary phase method is often employed for computing tunneling {\em
phase} times of analytically-continuous {\em gaussian} or infinite-bandwidth
step pulses which collide with a potential barrier. The indiscriminate
utilization of this method without considering the barrier boundary effects
leads to some misconceptions in the interpretation of the phase times. After
reexamining the above barrier diffusion problem where we notice the wave packet
collision necessarily leads to the possibility of multiple reflected and
transmitted wave packets, we study the phase times for tunneling/reflecting
particles in a framework where an idea of multiple wave packet decomposition is
recovered. To partially overcome the analytical incongruities which rise up
when tunneling phase time expressions are obtained, we present a theoretical
exercise involving a symmetrical collision between two identical wave packets
and a one dimensional squared potential barrier where the scattered wave
packets can be recomposed by summing the amplitudes of simultaneously reflected
and transmitted waves.Comment: 32 pages, 5 figures, 1 tabl
Dietary Inclusion of Colicin E1 Prevents Post-weaning Diarrhea in Pigs
Including a purified antimicrobial peptide, Colicin E1, at a rate of 22mg/kg diet in a corn-soy based diet for weanling pigs prevented experimentally induced (E. coli F18) post-weaning diarrhea. Colicins may be an effective alternative to conventional antibiotics for use in animal feed
Colliding Black Holes: The Close Limit
The problem of the mutual attraction and joining of two black holes is of
importance as both a source of gravitational waves and as a testbed of
numerical relativity. If the holes start out close enough that they are
initially surrounded by a common horizon, the problem can be viewed as a
perturbation of a single black hole. We take initial data due to Misner for
close black holes, apply perturbation theory and evolve the data with the
Zerilli equation. The computed gravitational radiation agrees with and extends
the results of full numerical computations.Comment: 4 pages, Revtex, 3 postscript figures included, CGPG-94/2-
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