1,772 research outputs found
Proof of vanishing cohomology at the tachyon vacuum
We prove Sen's third conjecture that there are no on-shell perturbative
excitations of the tachyon vacuum in open bosonic string field theory. The
proof relies on the existence of a special state A, which, when acted on by the
BRST operator at the tachyon vacuum, gives the identity. While this state was
found numerically in Feynman-Siegel gauge, here we give a simple analytic
expression.Comment: 19 pages, 4 figures; v2: references adde
A spatially implicit model fails to predict the structure of spatially explicit metacommunities under high dispersal
Rolling to the tachyon vacuum in string field theory
We argue that the rolling-tachyon solution in cubic OSFT proceeds at late
times to precisely the analytic tachyon-vacuum solution constructed by Schnabl.
In addition, we demonstrate the relationship between the rolling-tachyon
solution and the standard BCFT description by showing that there is a finite
gauge transformation which relates the two.Comment: 16 pages, 5 figures, References and comments adde
How tropical epiphytes at the Eden Project contribute to rainforest canopy science
Understanding the ecological patterns and ecosystem processes of tropical rainforest canopies is becoming increasingly urgent in the face of widespread deforestation. However, accessing rainforest canopies is far from simple, and performing manipulative experiments in the canopy is particularly challenging. Botanic gardens provide an ideal ‘halfway house’ between field experiments and controlled laboratory conditions. As an ideal venue for testing equipment and refining ideas, botanic gardens also provide scientists with a direct route to public engagement, and potentially to research impact. Here we describe the ‘fernarium’, an adjustable canopy research platform for the standardisation, manipulation and detailed study of epiphytic bird’s nest ferns (Asplenium nidus) at the Eden Project in Cornwall. The fernarium provides a platform not only for the scientific study of bird’s nest ferns, but for public engagement, science communication and a wider understanding of the urgent environmental issues surrounding tropical rainforests. We include some preliminary resultsfrom an experiment in which the microbial community of a fern soil at the Eden Project was found to be similar in composition to that of a fern from lowland tropical rainforest in Malaysian Borneo. This study illustrates how preliminary experiments in an indoor rainforest can inform experimental techniques and procedures fundamental to the scientific study of genuine rainforest canopies
Female teat size is a reliable indicator of annual breeding success in European badgers: Genetic validation
Assessing which females have bred successfully is a central requirement in many ecological field studies,
providing an estimate of the effective female population size. Researchers have applied teat measurements
previously to assess whether females, in a variety of mammalian species, have bred; however, this
technique has not been validated genetically. Furthermore, several analytical techniques are available to
classify individuals, but their misclassification rates have not been compared. We used 22 microsatellite
loci to assign maternity, with 95% confidence, within a high-density population of European badgers Meles
meles, as plural and subterranean breeding means that maternity cannot be inferred from behavioural
observations. The teat lengths and diameters of 136 females, measured May–July 1994–2005, from social
groups in which all offspring were assigned a mother, were reliable indicators of recent breeding success.
A Generalised Linear Mixed Model (GLMM) classified both breeding and non-breeding females with
lower error rates than discriminant analyses and crude teat-size criteria. The GLMM model logit probability
=
−20 + 1.8 month + 1.6 mean teat length + 1.0 mean teat diameter can be applied quickly in the field
to assess the probability with which a female badger should be assigned maternity. This is a low-cost
measure which, after validation, could be used in other badger or mammalian populations to assess the
breeding success of females. This may be a particularly useful welfare tool for veterinary practitioners,
especially during badger culls
Superstring field theory equivalence: Ramond sector
We prove that the finite gauge transformation of the Ramond sector of the
modified cubic superstring field theory is ill-defined due to collisions of
picture changing operators.
Despite this problem we study to what extent could a bijective classical
correspondence between this theory and the (presumably consistent)
non-polynomial theory exist. We find that the classical equivalence between
these two theories can almost be extended to the Ramond sector: We construct
mappings between the string fields (NS and Ramond, including Chan-Paton factors
and the various GSO sectors) of the two theories that send solutions to
solutions in a way that respects the linearized gauge symmetries in both sides
and keeps the action of the solutions invariant. The perturbative spectrum
around equivalent solutions is also isomorphic.
The problem with the cubic theory implies that the correspondence of the
linearized gauge symmetries cannot be extended to a correspondence of the
finite gauge symmetries. Hence, our equivalence is only formal, since it
relates a consistent theory to an inconsistent one. Nonetheless, we believe
that the fact that the equivalence formally works suggests that a consistent
modification of the cubic theory exists. We construct a theory that can be
considered as a first step towards a consistent RNS cubic theory.Comment: v1: 24 pages. v2: 27 pages, significant modifications of the
presentation, new section, typos corrected, references adde
Misunderstanding of Front-Of-Package Nutrition Information on US Food Products.
Front-of-package nutrition symbols (FOPs) are presumably readily noticeable and require minimal prior nutrition knowledge to use. Although there is evidence to support this notion, few studies have focused on Facts Up Front type symbols which are used in the US. Participants with varying levels of prior knowledge were asked to view two products and decide which was more healthful. FOPs on packages were manipulated so that one product was more healthful, allowing us to assess accuracy. Attention to nutrition information was assessed via eye tracking to determine what if any FOP information was used to make their decisions. Results showed that accuracy was below chance on half of the comparisons despite consulting FOPs. Negative correlations between attention to calories, fat, and sodium and accuracy indicated that consumers over-relied on these nutrients. Although relatively little attention was allocated to fiber and sugar, associations between attention and accuracy were positive. Attention to vitamin D showed no association to accuracy, indicating confusion surrounding what constitutes a meaningful change across products. Greater nutrition knowledge was associated with greater accuracy, even when less attention was paid. Individuals, particularly those with less knowledge, are misled by calorie, sodium, and fat information on FOPs
Relationships among food label use, motivation, and dietary quality.
Nutrition information on packaged foods supplies information that aids consumers in meeting the recommendations put forth in the US Dietary Guidelines for Americans such as reducing intake of solid fats and added sugars. It is important to understand how food label use is related to dietary intake. However, prior work is based only on self-reported use of food labels, making it unclear if subjective assessments are biased toward motivational influences. We assessed food label use using both self-reported and objective measures, the stage of change, and dietary quality in a sample of 392 stratified by income. Self-reported food label use was assessed using a questionnaire. Objective use was assessed using a mock shopping task in which participants viewed food labels and decided which foods to purchase. Eye movements were monitored to assess attention to nutrition information on the food labels. Individuals paid attention to nutrition information when selecting foods to buy. Self-reported and objective measures of label use showed some overlap with each other (r=0.29, p<0.001), and both predicted dietary quality (p<0.001 for both). The stage of change diminished the predictive power of subjective (p<0.09), but not objective (p<0.01), food label use. These data show both self-reported and objective measures of food label use are positively associated with dietary quality. However, self-reported measures appear to capture a greater motivational component of food label use than do more objective measures
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