14,144 research outputs found
Language-universal constraints on the segmentation of English
Two word-spotting experiments are reported that examine whether the Possible-Word Constraint (PWC) [1] is a language-specific or language-universal strategy for the segmentation of continuous speech. The PWC disfavours parses which leave an impossible residue between the end of a candidate word and a known boundary. The experiments examined cases where the residue was either a CV syllable with a lax vowel, or a CVC syllable with a schwa. Although neither syllable context is a possible word in English, word-spotting in both contexts was easier than with a context consisting of a single consonant. The PWC appears to be language-universal rather than language-specific
Lunar nitrogen: Secular variation or mixing?
The two current models to explain the nearly 40% variation of the lunar nitrogen isotopic composition are: (1) secular variation of solar wind nitrogen; and (2) a two component mixing model having a constant, heavy solar wind admixed with varying amounts of indigenous light lunar N (LLN). Both models are needed to explain the step pyrolysis extraction profile. The secular variation model proposes that the low temperature release is modern day solar wind implanted into grain surfaces, the 900 C to 1100 C release is from grain surfaces which were once exposed to the ancient solar wind but which are now trapped inside agglutinates, and the >1100 C release as spallogenic N produced by cosmic rays. The mixing model ascribes the components to solar wind, indigenous lunar N and spallogenic N respectively. An extension of either interpretation is that the light N seen in lunar breccias or deep drill cores represent conditions when more N-14 was available to the lunar surface
Overlay copy technique to provide high-contrast electron micrographs for automatic metallographic analysis
Overlay copy technique to provide high-contrast electron micrographs for automatically determining quantitative microstructure of multiphase specimen
Evaluations of Space Shielding
A general method of evaluating the efficiency of space vehicle shielding is developed and used to compare various active and passive systems for protection against ionizing radiation. Available permanent magnets are found useless for active shielding, and combined active-passive systems in general are determined to be inefficient. On the other hand, evaluations show that active electrostatic shielding may have possibilities for weight savings if electrical conditions (presently unknown) are favorable therefor in space. Further, a positive potential improvement is calculated for an active shielding system which utilizes superconducting Nb3Sn to provide a confined magnetic flux to deflect incident charged particles; this potential points toward substantial reductions in shield weight for the protection of large vehicles from highly energetic particles. Recommendations are made for further research, particularly for flight experiments to measure directionality of solar flare protons
Comment on "Self-Purification in Semiconductor Nanocrystals"
In a recent Letter [PRL 96, 226802 (2006)], Dalpian and Chelikowsky claimed
that formation energies of Mn impurities in CdSe nanocrystals increase as the
size of the nanocrystal decreases, and argued that this size dependence leads
to "self-purification" of small nanocrystals. They presented
density-functional-theory (DFT) calculations showing a strong size dependence
for Mn impurity formation energies, and proposed a general explanation. In this
Comment we show that several different DFT codes, pseudopotentials, and
exchange-correlation functionals give a markedly different result: We find no
such size dependence. More generally, we argue that formation energies are not
relevant to substitutional doping in most colloidally grown nanocrystals.Comment: 1 page, 1 figur
The life and health challenges of young Malaysian couples: results from a stakeholder consensus and engagement study to support non-communicable disease prevention
BACKGROUND: Malaysia faces burgeoning obesity and diabetes epidemics with a 250% and 88% increase respectively between 1996 and 2006. Identifying the health challenges of young adults in Malaysia, who constitute 27.5 % of the population, is critical for NCD prevention. The aim of the study was two-fold: (1) to achieve consensus amongst stakeholders on the most important challenge impacting the health of young adults, and (2) to engage with stakeholders to formulate a NCD prevention framework.METHODS: The Delphi Technique was utilised to achieve group consensus around the most important life and health challenges that young adults face in Malaysia. Subsequently, the results of the consensus component were shared with the stakeholders in an engagement workshop to obtain input on a NCD prevention framework.RESULTS: We found that life stress was a significant concern. It would seem that the apathy towards pursuing or maintaining a healthy lifestyle among young adults may be significantly influenced by the broader distal determinant of life stress. The high cost of living is suggested to be the main push factor for young working adults towards attaining better financial security to improve their livelihood. In turn, this leads to a more stressful lifestyle with less time to focus on healthier lifestyle choices.CONCLUSIONS: The findings highlight a pivotal barrier to healthier lifestyles. By assisting young adults to cope with daily living coupled with realistic opportunities to make healthier dietary choices, be more active, and less sedentary could assist in the development of NCD health promotion strategies<br/
A wider audience: Turning VLBI into a survey instrument
Radio observations using the Very Long Baseline Interferometry (VLBI)
technique typically have fields of view of only a few arcseconds, due to the
computational problems inherent in imaging larger fields. Furthermore,
sensitivity limitations restrict observations to very compact and bright
objects, which are few and far between on the sky. Thus, while most branches of
observational astronomy can carry out sensitive, wide-field surveys, VLBI
observations are limited to targeted observations of carefully selected
objects. However, recent advances in technology have made it possible to carry
out the computations required to target hundreds of sources simultaneously.
Furthermore, sensitivity upgrades have dramatically increased the number of
objects accessible to VLBI observations. The combination of these two
developments have enhanced the survey capabilities of VLBI observations such
that it is now possible to observe (almost) any point in the sky with
milli-arcsecond resolution. In this talk I review the development of wide-field
VLBI, which has made significant progress over the last three years.Comment: Invited review at the General Assembly of the Astronomische
Gesellschaf
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