3,772 research outputs found
Entanglement Generation in the Scattering of One-Dimensional Particles
This article provides a convenient framework for quantitative evaluation of
the entanglement generated when two structureless, distinguishable particles
scatter non-relativistically in one dimension. It explores how three factors
determine the amount of entanglement generated: the momentum distributions of
the incoming particles, their masses, and the interaction potential. Two
important scales emerge, one set by the kinematics and one set by the dynamics.
This method also provides two approximate analytic formulas useful for
numerical evaluation of entanglement and reveals an interesting connection
between purity, linear coordinate transformations, and momentum uncertainties.Comment: 11 pages, submitted to PR
The narratology of Jennifer Johnston\u27s novels
Irish novelist Jennifer Johnston has published twelve novels to date, from The Captains and the Kings in 1972 to The Gingerbread Woman in 2000. Eileen Battersby\u27s recent Irish Times article âMaking Sense of Lifeâ called her âthe quiet woman of Irish fiction, â referring to her understated, sophisticated writing style. All of her novels are short (Joseph Connelly and others have called them ânovellasâ), and she has become known for her ability to describe a complex situation in a direct, compact way.
This discussion is intended to investigate the narratology of several Johnston novels: to explore narrative voice, narrative chronology, influence of the implied author on the reader, and other narratological characteristics. Specifically, there will be discussions of two earlier novels which use few specialized narrative âtricksâ and two later ones in which specific narrative devices play significant roles. Finally, Johnstonâs latest novel will be examined with respect to the observations made on earlier ones
Differences between European birthweight standards: impact on classification of âsmall for gestational ageâ
We describe a quantitative and comparative review of a selection of European birthweight standards for gestational age for singletons, to enable appropriate choices to be made for clinical and research use. Differences between median values at term across standards in 10 regions and misclassification of âsmall for gestational ageâ (SGA), were studied. Sex and parity differences, exclusion criteria, and methods of construction were considered. There was wide variation between countries in exclusion criteria, methods of calculating standards, and median birthweight at term. The lightest standards (e.g. France's medians are 255g lower than Norway's medians) were associated with fewer exclusion criteria. Up to 20% of the population used in the construction of the Scottish standard would be classified as SGA using the Norwegian standard. Substantial misclassification of SGA is possible. Assumptions about variation used in the construction of some standards were not justified. It is not possible to conclude that there are real differences in birthweight standards between European countries. Country-based standards control for some population features but add misclassification due to the differing ways in which standards are derived. Standards should be chosen to reflect clinical or research need. If standards stratified by sex or parity are not available, adjustments should be made. In multinational studies, comparisons should be made between results using both a common standard and country-based standards
Puzzling asteroid 21 Lutetia: our knowledge prior to the Rosetta fly-by
A wide observational campaign was carried out in 2004-2009 aimed to complete
the ground-based investigation of Lutetia prior to the Rosetta fly-by in July
2010. We have obtained BVRI photometric and V-band polarimetric measurements
over a wide range of phase angles, and visible and infrared spectra in the
0.4-2.4 micron range. We analyzed them together with previously published data
to retrieve information on Lutetia's surface properties. Values of lightcurve
amplitudes, absolute magnitude, opposition effect, phase coefficient and BVRI
colors of Lutetia surface seen at near pole-on aspect have been determined. We
defined more precisely parameters of polarization phase curve and showed their
distinct deviation from any other moderate-albedo asteroid. An indication of
possible variations both in polarization and spectral data across the asteroid
surface was found. To explain features found by different techniques we propose
that (i) Lutetia has a non-convex shape, probably due to the presence of a
large crater, and heterogeneous surface properties probably related to surface
morphology; (ii) at least part of the surface is covered by a fine-grained
regolith with particle size less than 20 microns; (iii) the closest meteorite
analogues of Lutetia's surface composition are particular types of carbonaceous
chondrites or Lutetia has specific surface composition not representative among
studied meteorites
On the interpretation of working memory span in adults.
Experimental research into childrenâs working memory span has shown that retention duration contributes substantially to span performance, while processing efficiency need not be related to concurrent memory load (Towse, Hitch, & Hutton, 1998). These findings have been used to argue for a model of working memory span that emphasizes time-based forgetting rather than the popular resource-sharing or tradeoff framework. The present paper considers whether adults perform working memory span tasks in a qualitatively different way. Data from reading span and operation span tasks show that adultsâ performance can be distinguished from that of children, but also that a task-switching model of working memory span can explain some important aspects of performance
A panchromatic analysis of starburst galaxy M82: Probing the dust properties
(Abridged) We combine NUV, optical and IR imaging of the nearby starburst
galaxy M82 to explore the properties of the dust both in the interstellar
medium of the galaxy and the dust entrained in the superwind. The three NUV
filters of Swift/UVOT enable us to probe in detail the properties of the
extinction curve in the region around the 2175A bump. The NUV colour-colour
diagram strongly rules out a Calzetti-type law, which can either reflect
intrinsic changes in the dust properties or in the star formation history
compared to starbursts well represented by such an attenuation law. We
emphasize that it is mainly in the NUV region where a standard Milky-Way-type
law is preferred over a Calzetti law. The age and dust distribution of the
stellar populations is consistent with the scenario of an encounter with M81 in
the recent 400 Myr. The radial gradients of the NUV and optical colours in the
superwind region support the hypothesis that the emission in the wind cone is
driven by scattering from dust grains entrained in the ejecta. The observed
wavelength dependence reveals either a grain size distribution , where is the size of the grain, or a flatter distribution with a
maximum size cutoff, suggesting that only small grains are entrained in the
supernovae-driven wind.Comment: 12 pages, 12 figures, 3 tables, MNRAS, in pres
On the nature of the relationship between processing activity and item retention in children.
The concept of working memory emphasizes the interrelationship between the transient retention of information and concurrent processing activity. Three experiments address this relationship in children between 8 and 17 years of age by examining forgetting when a processing task is interpolated between presentation and recall of the memory items. Unlike previous studies, delivery of interpolated stimuli was under computer control and responses to these stimuli were timed. There were consistent effects of the duration of the interpolated task, but no effects of either its difficulty or similarity to memory material and no qualitative developmental differences in task performance. The absence of an effect of difficulty provides no support for models of working memory in which limited capacity is shared between the dual functions of processing and storage, but is compatible with an alternative âtask switchingâ account. However, task switching did not explain developmental differences in recall. Other aspects of the results suggest that there can be interactions between processing and storage but it is argued that these cannot be straightforwardly explained in terms of either task switching or resource sharing
Foraminifera of the upper limestone group of the Scottish carboniferous
No abstract available
A systematic review reveals conflicting evidence for the prevalence of antibodies against the sialic acid âxenoautoantigenâ Neu5Gc in humans and the need for a standardised approach to quantification
Copyright \ua9 2024 Hutton, Scott, Robson, Signoret and Fascione.Despite an array of hypothesised implications for health, disease, and therapeutic development, antibodies against the non-human sialic acid N-glycolylneuraminic acid (Neu5Gc) remain a subject of much debate. This systematic review of 114 publications aimed to generate a comprehensive overview of published studies in this field, addressing both the reported prevalence of anti-Neu5Gc antibodies in the human population and whether experimental variation accounts for the conflicting reports about the extent of this response. Absolute titres of anti-Neu5Gc antibodies, the reported prevalence of these antibodies, and the individual variation observed within experiments were analysed and grouped according to biological context (âinflammationâ, âxenotransplantationâ, âbiotherapeutic useâ, âcancerâ, and âhealthy populationsâ), detection method, target epitope selection, and choice of blocking agent. These analyses revealed that the experimental method had a notable impact on both the reported prevalence and absolute titres of anti-Neu5Gc antibodies in the general population, thereby limiting the ability to ascribe reported trends to genuine biological differences or the consequence of experimental design. Overall, this review highlights important knowledge gaps in the study of antibodies against this important xenoautoantigen and the need to establish a standardised method for their quantification if the extent of the importance of Neu5Gc in human health is to be fully understood
HiHi fMRI: A data-reordering method for measuring the hemodynamic response of the brain with high temporal resolution and high SNR
There is emerging evidence that sampling the blood-oxygen-level-dependent (BOLD) response with high temporal resolution opens up new avenues to study the in vivo functioning of the human brain with functional magnetic resonance imaging. Because the speed of sampling and the signal level are intrinsically connected in magnetic resonance imaging via the T1 relaxation time, optimization efforts usually must make a trade-off to increase the temporal sampling rate at the cost of the signal level. We present a method, which combines a sparse event-related stimulus paradigm with subsequent data reshuffling to achieve high temporal resolution while maintaining high signal levels (HiHi). The proof-of-principle is presented by separately measuring the single-voxel time course of the BOLD response in both the primary visual and primary motor cortices with 100-ms temporal resolution
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