Digital manipulation of faces and its consequence upon identification and attractiveness

The thesis investigated perception of facial identity and attractiveness with digital manipulation of facial traits. A presentation time paradigm was developed by which stimuli could be presented for a range of brief display periods. Using this paradigm subjects recognised photo-realistic target faces caricatured in shape with greater accuracy than veridical images consistent with previous findings using reaction time as a measure. Subjects were further required to identify colour representations of famous faces which were either veridical, caricatured in colour space or had enhanced colour saturation and intensity contrast (as contrast controls). Recognition accuracy was greater when viewing the colour-caricatured stimuli than either the veridical images or the contrast controls. The removal of colour to produce grey-scale images also decreased accuracy of face recognition indicating that colour information aids facial identification. Caricaturing of faces, therefore, can be extended to the colour domain and, as with shape caricaturing, enhancement of distinctive information can produce a recognition advantage for famous faces. Subjects were also asked to identify the best-likeness for individuals using photo-realistic stimuli and an interactive paradigm with shape-caricature, colour-caricature and contrast-control varied by the user in real-time. The best-likeness with shape manipulation was a slight anti-caricature while with colour-caricature and contrast-control images a mildly exaggerated image was selected as the best-likeness. Thus although images caricatured substantially in colour or shape (+40%) induce superior recognition compared to veridical images such substantial exaggerations are not seen as best-likenesses under prolonged exposure. The gender typicality for white British and Japanese composite faces was manipulated and subjects presented with the images using both a static forced-choice paradigm and an interactive paradigm. Male and female face shapes with enhanced feminine features were consistently found to be more attractive than average. Preference for enhanced femininity for female faces was greater for subjects making within- than cross-cultural judgements

Polarization transitions in interacting ring 1D arrays

Periodic nanostructures can display the dynamics of arrays of atoms while enabling the tuning of interactions in ways not normally possible in Nature. We examine one dimensional arrays of a ``synthetic atom,'' a one dimensional ring with a nearest neighbor Coulomb interaction. We consider the classical limit first, finding that the singly charged rings possess antiferroelectric order at low temperatures when the charge is discrete, but that they do not order when the charge is treated as a continuous classical fluid. In the quantum limit Monte Carlo simulation suggests that the system undergoes a quantum phase transition as the interaction strength is increased. This is supported by mapping the system to the 1D transverse field Ising model. Finally we examine the effect of magnetic fields. We find that a magnetic field can alter the electrostatic phase transition producing a ferroelectric groundstate, solely through its effect of shifting the eigenenergies of the quantum problem.Comment: 12 pages in two column format, 18 figure

Mass Azithromycin Distribution and Community Microbiome: A Cluster-Randomized Trial.

BackgroundMass distributions of oral azithromycin have long been used to eliminate trachoma, and they are now being proposed to reduce childhood mortality. The observed benefit appears to be augmented with each additional treatment, suggesting a possible community-level effect. Here, we assess whether 2 biannual mass treatments of preschool children affect the community's gut microbiome at 6 months after the last distribution.MethodsIn this cluster-randomized controlled trial, children aged 1-60 months in the Dossa region of Niger were randomized at the village level to receive a single dose of azithromycin or placebo every 6 months. Fecal samples were collected 6 months after the second treatment for metagenomic deep sequencing. The prespecified primary outcome was the Euclidean PERMANOVA of the gut microbiome, or effectively the distance between the genus-level centroid at the community level, with the secondary outcome being the Simpson's α diversity.ResultsIn the azithromycin arm, the gut microbial structures were significantly different than in the placebo arm (Euclidean PERMANOVA, P < .001). Further, the diversity of the gut microbiome in the azithromycin arm was significantly lower than in the placebo arm (inverse Simpson's index, P = .005).ConclusionsTwo mass azithromycin administrations, 6 months apart, in preschool children led to long-term alterations of the gut microbiome structure and community diversity. Here, long-term microbial alterations in the community did not imply disease but were associated with an improvement in childhood mortality.Clinical trials registrationNCT02048007

Birth order does not affect ability to detect kin

Previous studies suggest that birth order affects kinship detection ability. Kaminski et al. (2010) argued that firstborns use contextual cues (e.g., maternal perinatal association) to assess kinship in their own family, leading to a disadvantage in assessing kinship from facial cues alone in strangers. In contrast, laterborns do not have the contextual cue of maternal perinatal association and hence rely more on facial cues, leading to an advantage in detecting kin from facial cues alone. However, Alvergne et al. (2010) found no evidence in support of such a birthorder effect. The current study aimed to replicate previous studies with better suited methods to determine the effect of birth order on kin recognition. 109 raters viewed 132 pairs of photographs of children (aged 3-17 years), and indicated whether each pair was related or unrelated. Half of the pairs were sibling pairs and half were unrelated child pairs that were age- and gender- matched to the related pairs. No image was shown more than once, related pairs were not known to be related to any other image in the study, and individuals from unrelated pairs were not known to be related to any other image. We used binomial logistic mixed effects modelling to predict kinship judgments from relatedness and birth order (with image pair and rater as random factors). Relatedness was the main factor driving kinship judgments; related child-pairs were more than twice as likely as unrelated pairs to be judged as kin. Kinship judgment accuracy was unaffected by rater birth order. These findings indicate that laterborns did not have an advantage in detecting child sibling pairs. Pre-registration, data, code, and preprint available at osf.io/h43ep

Contribution of shape and surface reflectance information to kinship detection in 3D face images

Previous research has established that humans are able to detect kinship among strangers from facial images alone. The current study investigated what facial information is used for making those kinship judgments, specifically the contribution of face shape and surface reflectance information (e.g., skin texture, tone, eye and eyebrow color). Using 3D facial images, 195 participants were asked to judge the relatedness of 100 child pairs, half of which were related and half of which were unrelated. Participants were randomly assigned to judge one of three stimulus versions: face images with both surface reflectance and shape information present (reflectance and shape version), face images with shape information removed but surface reflectance present (reflectance version), or face images with surface reflectance information removed but shape present (shape version). Using binomial logistic mixed models, we found that participants were able to detect relatedness at levels above chance for all three stimulus versions. Overall, both individual shape and surface reflectance information contribute to kinship detection, and both cues are optimally combined when presented together. Preprint, preregistration, code, and data are available on the Open Science Framework (osf.io/7ftxd)

Cancer incidence among children and young adults who have undergone x-ray guided cardiac catheterization procedures

Children and young adults with heart disease appear to be at increased risk of developing cancer, although the reasons for this are unclear. A cohort of 11,270 individuals, who underwent cardiac catheterizations while aged B 22 years in the UK, was established from hospital records. Radiation doses from cardiac catheterizations and CT scans were estimated. The cohort was matched with the NHS Central Register and NHS Transplant Registry to determine cancer incidence and transplantation status. Standardized incidence ratios (SIR) with associated confidence intervals (CI) were calculated. The excess relative risk (ERR) of lymphohaematopoietic neoplasia was also calculated using Poisson regression. The SIR was raised for all malignancies (2.32, 95% CI 1.65, 3.17), lymphoma (8.34, 95% CI 5.22, 12.61) and leukaemia (2.11, 95% CI 0.82, 4.42). After censoring transplant recipients, post-transplant, the SIR was reduced to 0.90 (95% CI 0.49, 1.49) for all malignancies. All lymphomas developed post-transplant. The SIR for all malignancies developing 5 years from the first cardiac catheterization (2 years for leukaemia/lymphoma) remained raised (3.01, 95% CI 2.09, 4.19) but was again reduced after censoring transplant recipients (0.98, 95% CI 0.48, 1.77). The ERR per mGy bone marrow dose for lympho-haematopoietic neoplasia was reduced from 0.541 (95% CI 0.104, 1.807) to 0.018 (95% CI - 0.002, 0.096) where transplantation status was accounted for as a time-dependent background risk factor. In conclusion, transplantation appears to be a large contributor to elevated cancer rates in this patient group. This is likely to be mainly due to associated immunosuppression, however, radiation exposure may also be a contributing factor

Kin recognition and perceived facial similarity

Facial similarity between individuals informs kinship judgments in third-party kin recognition. Indeed, one study found that similarity and kinship judgments encapsulate the same information (Maloney & Dal Martello, 2006). Yet, another study found that this is not the case when comparing adult face pairs of different sex (DeBruine et al., 2009). We replicated these studies to further clarify the role of facial similarity in kin recognition. We recruited 318 raters, who were shown 50 sibling pairs and 50 age- and sex-matched unrelated pairs ranging from 3 to 17 years old. Each rater was randomly assigned to make either kinship judgments (“related” or “unrelated”) or similarity judgments (scale from 0 [not very similar] to 10 [very similar]). The threshold model found that performance in both tasks was equally accurate, with participants detecting child siblings in the kinship task above chance and giving significantly higher similarity ratings to siblings in the similarity task. In both tasks, opposite-sex siblings were perceived to be siblings less often than same-sex siblings, and judgments of unrelated face pairs were not affected by the sex of faces. Conversely, the effect of age difference within pairs of faces differed for the two tasks: a greater age difference decreased all kinship judgments, but only decreased similarity judgments of siblings, not unrelated pairs. In line with DeBruine et al. (2009), these findings suggest that similarity and kinship judgments are highly correlated but not strictly synonymous. The OSF Pre-registration Challenge for this project can be found at osf.io/ps9hy and the data at osf.io/sef9k

Facial expressions influence kin recognition accuracy

Kinship informs the allocation of pro-social and sexual behaviour. In addition to the ability to detect kin who are directly related to the observer, humans are also able to detect relatedness among others who are not related to themselves based on facial cues of relatedness. However, it is unclear what exact facial cues inform these kinship judgments. Facial expression might be one candidate, as it has been shown that a computer kin-detection algorithm can match relatives accurately when the stimuli are smiling. The current study investigated whether a smiling facial expression increases the accuracy of judging relatedness compared to a neutral facial expression in human raters. The stimuli were images of 50 sibling pairs and 50 unrelated pairs (aged 3-17 years) matched for age, ethnicity and sex. The stimuli included both neutral and smiling versions of each individual. Raters (N=77) were asked to judge whether the presented pairs were related or not in one of two counterbalanced versions of the study, where the same stimuli were never presented as both smiling and neutral to the same rater, and the expression within the pair was always the same. Binary relatedness judgments were analysed using binomial logistic mixed regression. Contrary to expectations, smiling decreased the accuracy of relatedness judgments compared to a neutral facial expression. When shown with a smiling expression compared to a neutral one, related pairs were judged to be related less often, while unrelated pairs were judged to be related more often. Evidence that the upper face is mostly used for kinship judgments suggests that smiles could distort or distract from other, more reliable cues of kinship. Pre-registration, data and code available at https://osf.io/58ewu/

An accurate effective action for `baby' to `adult' skyrmions

Starting with a Chern-Simons theory, we derive an effective action for interacting quantum Hall skyrmions that takes into account both large-distance physics and short-distance details as well. We numerically calculate the classical static skyrmion profile from this action and find excellent agreement with other, microscopic calculations over a wide range of skyrmion sizes including the experimentally relevant one. This implies that the essential physics of this regime might be captured by a continuum classical model rather than resorting to more microscopic approaches. We also show that the skyrmion energy closely follows the formula suggested earlier by Sondhi et al. for a broad parameter range of interest as well.Comment: 13 pages (Revtex) + 3 ps-figure

Recon 2.2: from reconstruction to model of human metabolism.

IntroductionThe human genome-scale metabolic reconstruction details all known metabolic reactions occurring in humans, and thereby holds substantial promise for studying complex diseases and phenotypes. Capturing the whole human metabolic reconstruction is an on-going task and since the last community effort generated a consensus reconstruction, several updates have been developed.ObjectivesWe report a new consensus version, Recon 2.2, which integrates various alternative versions with significant additional updates. In addition to re-establishing a consensus reconstruction, further key objectives included providing more comprehensive annotation of metabolites and genes, ensuring full mass and charge balance in all reactions, and developing a model that correctly predicts ATP production on a range of carbon sources.MethodsRecon 2.2 has been developed through a combination of manual curation and automated error checking. Specific and significant manual updates include a respecification of fatty acid metabolism, oxidative phosphorylation and a coupling of the electron transport chain to ATP synthase activity. All metabolites have definitive chemical formulae and charges specified, and these are used to ensure full mass and charge reaction balancing through an automated linear programming approach. Additionally, improved integration with transcriptomics and proteomics data has been facilitated with the updated curation of relationships between genes, proteins and reactions.ResultsRecon 2.2 now represents the most predictive model of human metabolism to date as demonstrated here. Extensive manual curation has increased the reconstruction size to 5324 metabolites, 7785 reactions and 1675 associated genes, which now are mapped to a single standard. The focus upon mass and charge balancing of all reactions, along with better representation of energy generation, has produced a flux model that correctly predicts ATP yield on different carbon sources.ConclusionThrough these updates we have achieved the most complete and best annotated consensus human metabolic reconstruction available, thereby increasing the ability of this resource to provide novel insights into normal and disease states in human. The model is freely available from the Biomodels database (http://identifiers.org/biomodels.db/MODEL1603150001)