1,769 research outputs found
Laboratory Determination of the Infrared Band Strengths of Pyrene Frozen in Water Ice: Implications for the Composition of Interstellar Ices
Broad infrared emission features (e.g., at 3.3, 6.2, 7.7, 8.6, and 11.3
microns) from the gas phase interstellar medium have long been attributed to
polycyclic aromatic hydrocarbons (PAHs). A significant portion (10%-20%) of the
Milky Way's carbon reservoir is locked in PAH molecules, which makes their
characterization integral to our understanding of astrochemistry. In molecular
clouds and the dense envelopes and disks of young stellar objects (YSOs), PAHs
are expected to be frozen in the icy mantles of dust grains where they should
reveal themselves through infrared absorption. To facilitate the search for
frozen interstellar PAHs, laboratory experiments were conducted to determine
the positions and strengths of the bands of pyrene mixed with H2O and D2O ices.
The D2O mixtures are used to measure pyrene bands that are masked by the strong
bands of H2O, leading to the first laboratory determination of the band
strength for the CH stretching mode of pyrene in water ice near 3.25 microns.
Our infrared band strengths were normalized to experimentally determined
ultraviolet band strengths, and we find that they are generally ~50% larger
than those reported by Bouwman et al. based on theoretical strengths. These
improved band strengths were used to reexamine YSO spectra published by Boogert
et al. to estimate the contribution of frozen PAHs to absorption in the 5-8
micron spectral region, taking into account the strength of the 3.25 micron CH
stretching mode. It is found that frozen neutral PAHs contain 5%-9% of the
cosmic carbon budget, and account for 2%-9% of the unidentified absorption in
the 5-8 micron region.Comment: Accepted for publication in ApJ on 14 Feb 201
Acceptability with general orderings
We present a new approach to termination analysis of logic programs. The
essence of the approach is that we make use of general orderings (instead of
level mappings), like it is done in transformational approaches to logic
program termination analysis, but we apply these orderings directly to the
logic program and not to the term-rewrite system obtained through some
transformation. We define some variants of acceptability, based on general
orderings, and show how they are equivalent to LD-termination. We develop a
demand driven, constraint-based approach to verify these
acceptability-variants.
The advantage of the approach over standard acceptability is that in some
cases, where complex level mappings are needed, fairly simple orderings may be
easily generated. The advantage over transformational approaches is that it
avoids the transformation step all together.
{\bf Keywords:} termination analysis, acceptability, orderings.Comment: To appear in "Computational Logic: From Logic Programming into the
Future
The impact of sound field systems on learning and attention in elementary school classrooms
Purpose: An evaluation of the installation and use of sound field systems (SFS) was carried out to investigate their impact on teaching and learning in elementary school classrooms. Methods: The evaluation included acoustic surveys of classrooms, questionnaire surveys of students and teachers and experimental testing of students with and without the use of SFS. Students ’ perceptions of classroom environments and objective data evaluating change in performance on cognitive and academic assessments with amplification over a six month period are reported. Results: Teachers were positive about the use of SFS in improving children’s listening and attention to verbal instructions. Over time students in amplified classrooms did not differ from those in nonamplified classrooms in their reports of listening conditions, nor did their performance differ in measures of numeracy, reading or spelling. Use of SFS in the classrooms resulted in significantly larger gains in performance in the number of correct items on the nonverbal measure of speed of processing and the measure of listening comprehension. Analysis controlling for classroom acoustics indicated that students ’ listening comprehension score
Inter-molecular structure factors of macromolecules in solution: integral equation results
The inter-molecular structure of semidilute polymer solutions is studied
theoretically. The low density limit of a generalized Ornstein-Zernicke
integral equation approach to polymeric liquids is considered. Scaling laws for
the dilute-to-semidilute crossover of random phase (RPA) like structure are
derived for the inter-molecular structure factor on large distances when
inter-molecular excluded volume is incorporated at the microscopic level. This
leads to a non-linear equation for the excluded volume interaction parameter.
For macromolecular size-mass scaling exponents, , above a
spatial-dimension dependent value, , mean field like density scaling
is recovered, but for the density scaling becomes non-trivial in
agreement with field theoretic results and justifying phenomenological
extensions of RPA. The structure of the polymer mesh in semidilute solutions is
discussed in detail and comparisons with large scale Monte Carlo simulations
are added. Finally a new possibility to determine the correction to scaling
exponent is suggested.Comment: 11 pages, 5 figures; to be published in Phys. Rev. E (1999
The production of nominal and verbal inflection in an agglutinative language: evidence from Hungarian
The contrast between regular and irregular inflectional morphology has been useful in investigating the functional and neural architecture of language. However, most studies have examined the regular/irregular distinction in non-agglutinative Indo-European languages (primarily English) with relatively simple morphology. Additionally, the majority of research has focused on verbal rather than nominal inflectional morphology. The present study attempts to address these gaps by introducing both plural and past tense production tasks in Hungarian, an agglutinative non-Indo-European language with complex morphology. Here we report results on these tasks from healthy Hungarian native-speaking adults, in whom we examine regular and irregular nominal and verbal inflection in a within-subjects design. Regular and irregular nouns and verbs were stem on frequency, word length and phonological structure, and both accuracy and response times were acquired. The results revealed that the regular/irregular contrast yields similar patterns in Hungarian, for both nominal and verbal inflection, as in previous studies of non-agglutinative Indo-European languages: the production of irregular inflected forms was both less accurate and slower than of regular forms, both for plural and past-tense inflection. The results replicate and extend previous findings to an agglutinative language with complex morphology. Together with previous studies, the evidence suggests that the regular/irregular distinction yields a basic behavioral pattern that holds across language families and linguistic typologies. Finally, the study sets the stage for further research examining the neurocognitive substrates of regular and irregular morphology in an agglutinative non-Indo-European language
Language control and parallel recovery of language in individuals with aphasia
Background: The causal basis of the different patterns of language recovery following stroke in bilingual speakers is not well understood. Our approach distinguishes the representation of language from the mechanisms involved in its control. Previous studies have suggested that difficulties in language control can explain selective aphasia in one language as well as pathological switching between languages. Here we test the hypothesis that difficulties in managing and resolving competition will also be observed in those who are equally impaired in both their languages even in the absence of pathological switching.
Aims: To examine difficulties in language control in bilingual individuals with parallel recovery in aphasia and to compare their performance on different types of conflict task.
Methods & procedures: Two right-handed, non-native English-speaking participants who showed parallel recovery of two languages after stroke and a group of non-native English-speaking, bilingual controls described a scene in English and in their first language and completed three explicit conflict tasks. Two of these were verbal conflict tasks: a lexical decision task in English, in which individuals distinguished English words from non-words, and a Stroop task, in English and in their first language. The third conflict task was a non-verbal flanker task.
Outcomes & Results: Both participants with aphasia were impaired in the picture description task in English and in their first language but showed different patterns of impairment on the conflict tasks. For the participant with left subcortical damage, conflict was abnormally high during the verbal tasks (lexical decision and Stroop) but not during the non-verbal flanker task. In contrast, for the participant with extensive left parietal damage, conflict was less abnormal during the Stroop task than the flanker or lexical decision task.
Conclusions: Our data reveal two distinct control impairments associated with parallel recovery. We stress the need to explore the precise nature of control problems and how control is implemented in order to develop fuller causal accounts of language recovery patterns in bilingual aphasia
Attribute and technology value mapping for conceptual product design phase
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Mechanical Engineering Science following peer review. The final, definite version of this paper has been published in Journal of Mechanical Engineering Science, Aris Georgiou, George Haritos, Moyra Fowler, and Yasmin Imani, ‘Attribute and technology value mapping for conceptual product design phase’, Vol. 230(11): 1745-1756, May 2016, published by SAGE Publishing, available online at doi: https://doi.org/10.1177/0954406215585595. Copyright © 2016 The Author(s).The main focus of this paper is how the concept design phase of the product development process can be improved by using an objective data-driven approach in selecting a final concept design to progress further. A quantitative new test-bed ‘Product Optimisation Value Engineering’ (PROVEN) is presented to critically assess new and evolving powertrain technologies at the concept design phase. The new test-bed has the ability to define a technology value map to assess multiple technical options as a function of its attributes, whose precise values can be determined at a given cost. A mathematical model that incorporates a highly adaptable, data-driven and multi-attribute value approach to product specification and conceptual design is developed, novel to the concept design process. This creates a substantially optimised product offering to the market, reducing overall development costs while achieving customer satisfactionPeer reviewe
Evaluating the effects of bilingual traffic signs on driver performance and safety
Variable Message Signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed
K2-138 g: Spitzer Spots a Sixth Planet for the Citizen Science System
K2 greatly extended Kepler's ability to find new planets, but it was typically limited to identifying transiting planets with orbital periods below 40 days. While analyzing K2 data through the Exoplanet Explorers project, citizen scientists helped discover one super-Earth and four sub-Neptune sized planets in the relatively bright (V = 12.21, K = 10.3) K2-138 system, all which orbit near 3:2 mean-motion resonances. The K2 light curve showed two additional transit events consistent with a sixth planet. Using Spitzer photometry, we validate the sixth planet's orbital period of 41.966 ± 0.006 days and measure a radius of 3.44_(-0.31)^(+0.32) R_⊕, solidifying K2-138 as the K2 system with the most currently known planets. There is a sizeable gap between the outer two planets, since the fifth planet in the system, K2-138 f, orbits at 12.76 days. We explore the possibility of additional nontransiting planets in the gap between f and g. Due to the relative brightness of the K2-138 host star, and the near resonance of the inner planets, K2-138 could be a key benchmark system for both radial velocity and transit-timing variation mass measurements, and indeed radial velocity masses for the inner four planets have already been obtained. With its five sub-Neptunes and one super-Earth, the K2-138 system provides a unique test bed for comparative atmospheric studies of warm to temperate planets of similar size, dynamical studies of near-resonant planets, and models of planet formation and migration
Maternal multiple micronutrient supplementation and other biomedical and socioenvironmental infl uences on children’s cognition at age 9–12 years in Indonesia: follow-up of the SUMMIT randomised trial
Background Brain and cognitive development during the fi rst 1000 days from conception are aff ected by multiple
biomedical and socioenvironmental determinants including nutrition, health, nurturing, and stimulation. An
improved understanding of the long-term infl uence of these factors is needed to prioritise public health investments
to optimise human development.
Methods We did a follow-up study of the Supplementation with Multiple Micronutrients Intervention Trial (SUMMIT),
a double-blind, cluster-randomised trial of maternal supplementation with multiple micronutrients (MMN) or iron
and folic acid (IFA) in Indonesia. Of 27 356 live infants from birth to 3 months of age in 2001–04, we re-enrolled
19 274 (70%) children at age 9–12 years, and randomly selected 2879 from the 18 230 who were attending school at a
known location. Of these, 574 children were oversampled from mothers who were anaemic or malnourished at
SUMMIT enrolment. We assessed the eff ects of MMN and associations of biomedical (ie, maternal and child
anthropometry and haemoglobin and preterm birth) and socioenvironmental determinants (ie, parental education,
socioeconomic status, home environment, and maternal depression) on general intellectual ability, declarative
memory, procedural memory, executive function, academic achievement, fi ne motor dexterity, and socioemotional
health. The SUMMIT trial was registered, number ISRCTN34151616.
Findings Children of mothers given MMN had a mean score of 0·11 SD (95% CI 0·01–0·20, p=0·0319) higher in
procedural memory than those given IFA, equivalent to the increase in scores with half a year of schooling. Children
of anaemic mothers in the MMN group scored 0·18 SD (0·06–0·31, p=0·0047) higher in general intellectual ability,
similar to the increase with 1 year of schooling. Overall, 18 of 21 tests showed a positive coeffi cient of MMN versus
IFA (p=0·0431) with eff ect sizes from 0·00–0·18 SD. In multiple regression models, socioenvironmental determinants
had coeffi cients of 0·00–0·43 SD and 22 of 35 tests were signifi cant at the 95% CI level, whereas biomedical
coeffi cients were 0·00–0·10 SD and eight of 56 tests were signifi cant, indicating larger and more consistent impact of
socioenvironmental factors (p<0·0001).
Interpretation Maternal MMN had long-term benefi ts for child cognitive development at 9–12 years of age, thereby
supporting its role in early childhood development, and policy change toward MMN. The stronger association of
socioenvironmental determinants with improved cognition suggests present reproductive, maternal, neonatal, and
child health programmes focused on biomedical determinants might not suffi ciently enhance child cognition, and
that programmes addressing socioenvironmental determinants are essential to achieve thriving populations
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