Explicit construction of nilpotent covariants in N=4 SYM

Some aspects of correlation functions in N=4 SYM are discussed. Using N=4 harmonic superspace we study two and three-point correlation functions which are of contact type and argue that these contact terms will not affect the non-renormalisation theorem for such correlators at non-coincident points. We then present a perturbative calculation of a five-point function at two loops in N=2 harmonic superspace and verify that it reproduces the derivative of the previously found four-point function with respect to the coupling. The calculation of this four-point function via the five-point function turns out to be significantly simpler than the original direct calculation. This calculation also provides an explicit construction of an N=2 component of an N=4 five-point nilpotent covariant that violates U(1)_Y symmetry.Comment: 20 pages, standard late

Natural Resources and Income Inequality in Developed Countries: Synthetic Control Method Evidence

We examine the causal effect of natural resource discoveries on income inequality using the synthetic control method on data from 1947 to 2009. We focus on the natural discoveries in Denmark, Netherlands, and Norway in the 1960–1970s and use top 1% and top 10% income share as the measure of income inequality. Many previous studies have been concerned that natural resources may increase income inequality. To the contrary, our results suggest that natural resources decrease income inequality or have no effect. We attribute this effect to the high institutional quality of countries we examine. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Horvath acknowledges the hospitality of the Leibniz Institute for East and Southeast European Studies, where he stayed as a visiting researcher. Horvath has been supported by Charles University Research Centre Program No. UNCE/HUM/035. Horvath and Horvathova acknowledge the support from the Czech Science Foundation Grant No. 20-18261S

Exploring salient dimensions in a free sorting task: A cross-country study within the elderly population

Free sorting tasks have been widely applied on different age segments to study the categorization of foods. However the method has received little attention in the investigation of older adults’ perception. Given the importance of understanding elderly perceptions in order to develop acceptable products, the main objective of this study was to investigate the factors that were able to affect the categorization of samples within different age segments of the healthy elderly consumers. Furthermore, in order to support the obtained configurations, the applicability of a free sorting task within different age segments of elderly population was investigated. The role of familiarity was considered to better understand the process of food categorization. A free sorting and a liking task were applied on French and Italian elderly to study perception and preference of familiar (peas) and less familiar (sweetcorn) vegetables. Similarities between the categorization maps, the preference maps and the sensory maps from vegetable samples were assessed through the RV coefficient and map visual inspection. Familiarity with the product was the main factor affecting the categorization among elderly. Categorization maps from a familiar vegetable were found to be suitable to obtain information on sensory and hedonic dimensions, while maps obtained from a less familiar vegetable mainly depicted sensory variability. The free sorting task was found to be a suitable method to use with healthy older adults, that allowed the detection of differences in the categorization of stimuli even among the more aged representatives of the elderly population

Increasing Vegetable Intakes: An Updated Systematic Review of Published Interventions

Vegetable consumption is important for a variety of health reasons, yet intakes are typically lower than recommended. Interventions to improve fruit and vegetable consumption are available, but these interventions are typically more successful for fruit consumption, while vegetable intakes remain low. This chapter details the interventions currently available that focus specifically on improving vegetable intakes. A systematic review of the published literature was conducted in 2015, and this has been updated for this chapter. Databases - PubMed, PsychInfo and Medline were searched over all years of records until January 2017 using pre-specified terms. Our searches identified 119 studies, detailing 206 interventions. Interventions aimed to use or change hedonic factors, such as taste, liking and familiarity (n=103), use or change environmental factors (n=54), use or change cognitive factors (n=28), or a combination of strategies (n=21). Increased vegetable acceptance, selection and/or consumption were reported to some degree in 186 (90%) interventions. Greatest success appears to be achieved in interventions that improve education, change the environment or use multiple approaches, but long-term success and cost-effectiveness are rarely considered. A focus on long-term benefits and sustained behaviour change is required

Nudging using the ‘dish of the day’ strategy does not work for plant-based meals in a Danish sample of adolescent and older people

© 2018 John Wiley & Sons Ltd Adequate nutrition is an important factor for health and well-being in adolescents and later years. Fruits and vegetables are part of a healthy diet as important source of nutrients, but their intakes are lower than the recommendations in European countries. This study aimed to compare the choices made by adolescents and older people between three similar dishes, one based on meat, one on fish and one on vegetables, in two different conditions: a neutral (control) situation and an intervention situation in which the vegetable-based meal was designated ‘dish of the day’. The comparisons of choices will be made within the same age group (adolescents in the control group vs. adolescents in the intervention group; older people in the control group vs. older people in the intervention group). A quasi-randomised field trial design was used with a sample of 94 adolescents (aged 10–19 years) and 97 older people (aged ≥65 years), who were randomly allocated to intervention or control groups. In the control situation participants were asked to choose between three similar meals, one meat, one fish and one the VeggiEat dish. In the intervention, the VeggiEat dish was labelled the ‘Dish of the day’. All dishes were provided free of charge, displayed side by side in the same order and served in same portions. The dish choices showed no differences between the control and intervention groups in both age groups, and no differences were found among the other variables analysed. This nudging strategy, ‘dish of the day’, seems not to work for the Danish sample of adolescents and older people. Future nudging studies with these populations are needed in order to find the best strategy to move adolescents' and older people's food habits toward a healthier pattern

Cycle-centrality in complex networks

Networks are versatile representations of the interactions between entities in complex systems. Cycles on such networks represent feedback processes which play a central role in system dynamics. In this work, we introduce a measure of the importance of any individual cycle, as the fraction of the total information flow of the network passing through the cycle. This measure is computationally cheap, numerically well-conditioned, induces a centrality measure on arbitrary subgraphs and reduces to the eigenvector centrality on vertices. We demonstrate that this measure accurately reflects the impact of events on strategic ensembles of economic sectors, notably in the US economy. As a second example, we show that in the protein-interaction network of the plant Arabidopsis thaliana, a model based on cycle-centrality better accounts for pathogen activity than the state-of-art one. This translates into pathogen-targeted-proteins being concentrated in a small number of triads with high cycle-centrality. Algorithms for computing the centrality of cycles and subgraphs are available for download

On twist-two operators in N=4 SYM

We propose a mechanism for calculating anomalous dimensions of higher-spin twist-two operators in N=4 SYM. We consider the ratio of the two-point functions of the operators and of their superconformal descendants or, alternatively, of the three-point functions of the operators and of the descendants with two protected half-BPS operators. These ratios are proportional to the anomalous dimension and can be evaluated at n-1 loop in order to determine the anomalous dimension at n loops. We illustrate the method by reproducing the well-known one-loop result by doing only tree-level calculations. We work out the complete form of the first-generation descendants of the twist-two operators and the scalar sector of the second-generation descendants.Comment: references added; typos correcte

Impact of a nudging intervention and factors associated with vegetable dish choice among European adolescents.

PURPOSE: To test the impact of a nudge strategy (dish of the day strategy) and the factors associated with vegetable dish choice, upon food selection by European adolescents in a real foodservice setting. METHODS: A cross-sectional quasi-experimental study was implemented in restaurants in four European countries: Denmark, France, Italy and United Kingdom. In total, 360 individuals aged 12-19 years were allocated into control or intervention groups, and asked to select from meat-based, fish-based, or vegetable-based meals. All three dishes were identically presented in appearance (balls with similar size and weight) and with the same sauce (tomato sauce) and side dishes (pasta and salad). In the intervention condition, the vegetable-based option was presented as the "dish of the day" and numbers of dishes chosen by each group were compared using the Pearson chi-square test. Multivariate logistic regression analysis was run to assess associations between choice of vegetable-based dish and its potential associated factors (adherence to Mediterranean diet, food neophobia, attitudes towards nudging for vegetables, food choice questionnaire, human values scale, social norms and self-estimated health, country, gender and belonging to control or intervention groups). All analyses were run in SPSS 22.0. RESULTS: The nudging strategy (dish of the day) did not show a difference on the choice of the vegetable-based option among adolescents tested (p = 0.80 for Denmark and France and p = 0.69 and p = 0.53 for Italy and UK, respectively). However, natural dimension of food choice questionnaire, social norms and attitudes towards vegetable nudging were all positively associated with the choice of the vegetable-based dish. Being male was negatively associated with choosing the vegetable-based dish. CONCLUSIONS: The "dish of the day" strategy did not work under the study conditions. Choice of the vegetable-based dish was predicted by natural dimension, social norms, gender and attitudes towards vegetable nudging. An understanding of factors related to choosing vegetable based dishes is necessary for the development and implementation of public policy interventions aiming to increase the consumption of vegetables among adolescents

Partial non-renormalisation of the stress-tensor four-point function in N=4 SYM and AdS/CFT

We show that, although the correlator of four stress-tensor multiplets in N=4 SYM is known to have radiative corrections, certain linear combinations of its components are protected from perturbative renormalisation and remain at their free-field values. This result is valid for weak as well as for strong coupling and for any gauge group. Our argument uses Intriligator's insertion formula, and includes a proof that the possible contact term contributions cannot change the form of the amplitudes. Combining this new non-renormalisation theorem with Maldacena's conjecture allows us to make a prediction for the structure of the corresponding correlator in AdS supergravity. This is verified by first considerably simplifying the strong coupling expression obtained by recent supergravity calculations, and then showing that it does indeed exhibit the expected structure.Comment: 21 pages, no figure

Supersymmetric null-surfaces

Single trace operators with the large R-charge in supersymmetric Yang-Mills theory correspond to the null-surfaces in $AdS_5\times S^5$. We argue that the moduli space of the null-surfaces is the space of contours in the super-Grassmanian parametrizing the complex $(2|2)$-dimensional subspaces of the complex $(4|4)$-dimensional space. The odd coordinates on this super-Grassmanian correspond to the fermionic degrees of freedom of the superstring.Comment: v4: added a reference to the earlier work; corrected the formula for the stabilizer of the BMN vacuum; added the discussion of the complex structure of the odd coordinates in Section 3.