Eta Carinae and the Luminous Blue Variables

We evaluate the place of Eta Carinae amongst the class of luminous blue variables (LBVs) and show that the LBV phenomenon is not restricted to extremely luminous objects like Eta Car, but extends luminosities as low as log(L/Lsun) = 5.4 - corresponding to initial masses ~25 Msun, and final masses as low as ~10-15 Msun. We present a census of S Doradus variability, and discuss basic LBV properties, their mass-loss behaviour, and whether at maximum light they form pseudo-photospheres. We argue that those objects that exhibit giant Eta Car-type eruptions are most likely related to the more common type of S Doradus variability. Alternative atmospheric models as well as sub-photospheric models for the instability are presented, but the true nature of the LBV phenomenon remains as yet elusive. We end with a discussion on the evolutionary status of LBVs - highlighting recent indications that some LBVs may be in a direct pre-supernova state, in contradiction to the standard paradigm for massive star evolution.Comment: 27 pages, 6 figures, Review Chapter in "Eta Carinae and the supernova imposters" (eds R. Humphreys and K. Davidson) new version submitted to Springe

Light echoes reveal an unexpectedly cool Eta Carinae during its 19th-century Great Eruption

Eta Carinae (Eta Car) is one of the most massive binary stars in the Milky Way. It became the second-brightest star in the sky during its mid-19th century "Great Eruption," but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique among known astronomical transients in that it exceeded the Eddington luminosity limit for 10 years. Because it is only 2.3 kpc away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that in its 19th century eruption, Eta Car ejected more than 10 M_solar in an event that had 10% of the energy of a typical core-collapse supernova without destroying the star. Here we report the discovery of light echoes of Eta Carinae which appear to be from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km/s, in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-G5 supergiant spectra, which have effective temperatures of ~5000 K. In contrast to the class of extragalactic outbursts assumed to be analogs of Eta Car's Great Eruption, the effective temperature of its outburst is significantly cooler than allowed by standard opaque wind models. This indicates that other physical mechanisms like an energetic blast wave may have triggered and influenced the eruption.Comment: Accepted for publication by Nature; 4 pages, 4 figures, SI: 6 pages, 3 figures, 5 table

Nano-cathodoluminescence reveals the effect of electron damage on the optical properties of nitride optoelectronics and the damage threshold

Nano-cathodoluminescence (Nano-CL) reveals optical emission from individual InGaN quantum wells for applications in optoelectronic devices. We show the luminescent intensity decays over time with exposure to the electron beam for energies between 80 and 200 keV. Measurements of the CL intensity over time show an exponential decline in intensity, which we propose is due to the formation of nitrogen Frenkel defects. The measured CL damage decreases with reductions in the electron accelerating voltage and we suggest that the electron induced structural damage may be suppressed below the proposed damage threshold. The electron beam induced damage leads to a non-radiative region that extends over the measured minority carrier diffusion length. Nano-CL may thus serve as a powerful technique to study III-nitride optoelectronics.This work was carried out with the support of the United Kingdom Engineering and Physical Sciences Research Council under Grant Nos. EP/NO17927/1 and EP/J003603/1. R. Oliver acknowledges funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013) ERC grant agreement number 279361 (MACONS) and the from the Royal Academy of Engineers/Leverhulme Trust senior research fellowship

The prognosis of allocentric and egocentric neglect : evidence from clinical scans

We contrasted the neuroanatomical substrates of sub-acute and chronic visuospatial deficits associated with different aspects of unilateral neglect using computed tomography scans acquired as part of routine clinical diagnosis. Voxel-wise statistical analyses were conducted on a group of 160 stroke patients scanned at a sub-acute stage. Lesion-deficit relationships were assessed across the whole brain, separately for grey and white matter. We assessed lesions that were associated with behavioural performance (i) at a sub-acute stage (within 3 months of the stroke) and (ii) at a chronic stage (after 9 months post stroke). Allocentric and egocentric neglect symptoms at the sub-acute stage were associated with lesions to dissociated regions within the frontal lobe, amongst other regions. However the frontal lesions were not associated with neglect at the chronic stage. On the other hand, lesions in the angular gyrus were associated with persistent allocentric neglect. In contrast, lesions within the superior temporal gyrus extending into the supramarginal gyrus, as well as lesions within the basal ganglia and insula, were associated with persistent egocentric neglect. Damage within the temporo-parietal junction was associated with both types of neglect at the sub-acute stage and 9 months later. Furthermore, white matter disconnections resulting from damage along the superior longitudinal fasciculus were associated with both types of neglect and critically related to both sub-acute and chronic deficits. Finally, there was a significant difference in the lesion volume between patients who recovered from neglect and patients with chronic deficits. The findings presented provide evidence that (i) the lesion location and lesion size can be used to successfully predict the outcome of neglect based on clinical CT scans, (ii) lesion location alone can serve as a critical predictor for persistent neglect symptoms, (iii) wide spread lesions are associated with neglect symptoms at the sub-acute stage but only some of these are critical for predicting whether neglect will become a chronic disorder and (iv) the severity of behavioural symptoms can be a useful predictor of recovery in the absence of neuroimaging findings on clinical scans. We discuss the implications for understanding the symptoms of the neglect syndrome, the recovery of function and the use of clinical scans to predict outcome

The Real Combination Problem : Panpsychism, Micro-Subjects, and Emergence

Panpsychism harbors an unresolved tension, the seriousness of which has yet to be fully appreciated. I capture this tension as a dilemma, and offer panpsychists advice on how to resolve it. The dilemma, briefly, is as follows. Panpsychists are committed to the perspicuous explanation of macro-mentality in terms of micro-mentality. But panpsychists take the micro-material realm to feature not just mental properties, but also micro-subjects to whom these properties belong. Yet it is impossible to explain the constitution of a macro-subject (like one of us) in terms of the assembly of micro-subjects, for, I show, subjects cannot combine. Therefore the panpsychist explanatory project is derailed by the insistence that the world’s ultimate material constituents (ultimates) are subjects of experience. The panpsychist faces a choice of abandoning her explanatory project, or recanting the claim that the ultimates are subjects. This is the dilemma. I argue that the latter option is to be preferred. This needn’t constitute a wholesale abandonment of panpsychism, however, since panpsychists can maintain that the ultimates possess phenomenal qualities, despite not being subjects of those qualities. This proposal requires us to make sense of phenomenal qualities existing independently of experiencing subjects, a challenge I tackle in the penultimate section. The position eventually reached is a form of neutral monism, so another way to express the overall argument is to say that, keeping true to their philosophical motivations, panpsychists should really be neutral monists.Peer reviewedFinal Accepted Versio

Eta Carinae -- Physics of the Inner Ejecta

Eta Carinae's inner ejecta are dominated observationally by the bright Weigelt blobs and their famously rich spectra of nebular emission and absorption lines. They are dense (n_e ~ 10^7 to 10^8 cm^-3), warm (T_e ~ 6000 to 7000 K) and slow moving (~40 km/s) condensations of mostly neutral (H^0) gas. Located within 1000 AU of the central star, they contain heavily CNO-processed material that was ejected from the star about a century ago. Outside the blobs, the inner ejecta include absorption-line clouds with similar conditions, plus emission-line gas that has generally lower densities and a wider range of speeds (reaching a few hundred km/s) compared to the blobs. The blobs appear to contain a negligible amount of dust and have a nearly dust-free view of the central source, but our view across the inner ejecta is severely affected by uncertain amounts of dust having a patchy distribution in the foreground. Emission lines from the inner ejecta are powered by photoionization and fluorescent processes. The variable nature of this emission, occurring in a 5.54 yr event cycle, requires specific changes to the incident flux that hold important clues to the nature of the central object.Comment: This is Chapter 5 in a book entitled: Eta Carinae and the Supernova Impostors, Kris Davidson and Roberta M. Humphreys, editors Springe

Report from the third international consensus meeting to harmonise core outcome measures for atopic eczema/dermatitis clinical trials (HOME).

This report provides a summary of the third meeting of the Harmonising Outcome Measures for Eczema (HOME) initiative held in San Diego, CA, U.S.A., 6-7 April 2013 (HOME III). The meeting addressed the four domains that had previously been agreed should be measured in every eczema clinical trial: clinical signs, patient-reported symptoms, long-term control and quality of life. Formal presentations and nominal group techniques were used at this working meeting, attended by 56 voting participants (31 of whom were dermatologists). Significant progress was made on the domain of clinical signs. Without reference to any named scales, it was agreed that the intensity and extent of erythema, excoriation, oedema/papulation and lichenification should be included in the core outcome measure for the scale to have content validity. The group then discussed a systematic review of all scales measuring the clinical signs of eczema and their measurement properties, followed by a consensus vote on which scale to recommend for inclusion in the core outcome set. Research into the remaining three domains was presented, followed by discussions. The symptoms group and quality of life groups need to systematically identify all available tools and rate the quality of the tools. A definition of long-term control is needed before progress can be made towards recommending a core outcome measure

Molecular marker analysis of Lr34 in Canada Western Red Spring wheat cultivars

Trabalho final de mestrado integrado em Medicina (Medicina Interna-Nutrição Clínica), apresentado à Faculdade de Medicina da Universidade de CoimbraO Carcinoma Colorretal é uma neoplasia frequente, particularmente nos Países Ocidentais, tendo-se observado um aumento na sua incidência em Portugal nos últimos 30 anos. Pensa-se que para este aumento tenha contribuído decisivamente a progressiva mudança do estilo de vida, particularmente no que diz respeito à alimentação e atividade física, tendencialmente reduzida. Vários estudos sugerem uma relação direta entre a alimentação e o CCR, ditando o possível papel da alimentação como fator de risco ou fator protetor de CCR. A carne vermelha e processada, bem como o consumo de álcool, estão frequentemente associados ao aumento de risco de CCR. Por outro lado, frutos, vegetais, outros alimentos ricos em fibras e peixe, associam-se a um risco diminuído de CCR. Os mecanismos subjacentes à alimentação não são ainda totalmente conhecidos. Até ao momento foram descritas funções essenciais dos componentes dietéticos na inibição ou progressão da inflamação do cólon, evento fundamental na carcinogénese colorretal e transversal a todas as situações de CCR. Objetivos: Comprovar a relação entre a alimentação e o risco de CCR; identificar quais os alimentos que estão associados a um aumento ou à diminuição do risco da doença; identificar os mecanismos subjacentes ao efeito potenciador ou protetor que os alimentos conferem; identificar através dos quais os alimentos interferem na carcinogénese colorretal; definir quais as estratégias necessárias para otimizar a prevenção primária desta doença. Métodos: Foi efetuada uma revisão pormenorizada com base na literatura recente e disponível na base de dados PubMed e B-on, referente ao possível papel da alimentação no desenvolvimento de Carcinoma Colorretal e os mecanismos pelos quais exerce a sua ação. Conclusões: os resultados dos estudos analisados sugerem que o CCR pode em grande parte percentagem de casos ser prevenido através do recurso à adoção de uma alimentação e estilo de vida saudáveis. As carnes vermelhas e processadas estão associadas a um aumento do risco desenvolver Carcinoma Colorretal, principalmente devido à produção de aminas heterocíclicas, devendo o seu consumo ser reduzido. or outro lado, o peixe produz um efeito oposto, exercendo um efeito protetor, principalmente através da diminuição da produção de mediadores pró-inflamatórios. Também os frutos e vegetais se associam a um risco menor de desenvolver esta neoplasia, devendo o seu consumo ser elevado. As propriedades quimiopreventivas destes alimentos devem-se, sobretudo, à inibição da inflamação no cólon, e também a mecanismos antioxidantes, pró-apoptóticos e de paragem do ciclo celular.Introduction: Colorectal carcinoma is a tumor with high incidence rate, particularly in Western countries, having been noticed an increase in incidence in Portugal in the past 30 years. It is widely accepted that progressive changes in lifestyle, regarding diet and reduced physical activity has decisively contributed to this increase. Several studies suggest a direct relationship between diet and CRC, dictating the possible role of diet as a risk factor or protective factor for CRC. Red and processed meat and alcohol consumption are often associated to increased risk of CRC. On the other hand, fruit, vegetables, other fiber rich foods and fish are associated to decreased risk of CRC. The underlying mechanisms of diet are not yet fully known. Up until now the essential functions of dietary components have been described as to inhibiting or helping to progress inflammations of the colon, the key event in colorectal carcinogenesis and transversal to all situations of CRC. Objectives: Demonstrate the relationship between diet and the risk of Colorectal Carcinoma; identify which food is associated with an increased or decreased risk of disease; identify the mechanisms of diet underlying the potentiating effect; determine necessary strategies to optimize the primary prevention of this disease. Methods: A detailed review was performed, based on the literature available on CRC and the mechanisms by which exerts its action. Conclusions: The results of the studies reviewed suggest that the CCR can be largely prevented by adopting a healthy diet and lifestyle. Red and processed meat are associated with increased risk of CRC, mainly due to the production of heterocyclic amines and its consumption should be reduced. On the other hand, fish produces an opposite effect, exerting a protective effect, mainly by decreasing the production of pro-inflammatory mediators. Fruit and vegetables are also associated with decreased risk of developing the disease, and its consumption should be increased. The chemopreventive properties of these foods are due mainly to the inhibition of colon inflammation, as well as antioxidant, pro-apoptotic and cell cycle arrest mechanisms

Age-related differences in selection by visual saliency

We examined the ability of older adults to select local and global stimuli varying in perceptual saliency – a task requiring non-spatial visual selection. Participants were asked to identify in separate blocks a target at either the global or local level of a hierarchical stimulus, while the saliency of each level was varied (across different conditions either the local or the global form was the more salient and relatively easier to identify). Older adults were less efficient than young adults in ignoring distractors that were higher in saliency than targets, and this occurred across both the global and local levels of form. The increased effects of distractor saliency on older adults occurred even when the effects were scaled by overall differences in task performance. The data provide evidence for an age-related decline in non spatial attentional selection of low-salient hierarchical stimuli, not determined by the (global or local) level at which selection was required. We discuss the implications of these results for understanding both the interaction between saliency and hierarchical processing and the effects of aging on non-spatial visual attention

Atypical disengagement from faces and its modulation by the control of eye fixation in children with Autism Spectrum Disorder

By using the gap overlap task, we investigated disengagement from faces and objects in children (9–17 years old) with and without autism spectrum disorder (ASD) and its neurophysiological correlates. In typically developing (TD) children, faces elicited larger gap effect, an index of attentional engagement, and larger saccade-related event-related potentials (ERPs), compared to objects. In children with ASD, by contrast, neither gap effect nor ERPs differ between faces and objects. Follow-up experiments demonstrated that instructed fixation on the eyes induces larger gap effect for faces in children with ASD, whereas instructed fixation on the mouth can disrupt larger gap effect in TD children. These results suggest a critical role of eye fixation on attentional engagement to faces in both groups