721 research outputs found
An obesogenic island in the Mediterranean: mapping potential drivers of obesity in Malta.
OBJECTIVE: The prevalence of childhood and adult obesity in Malta is among the highest in the world. Although increasingly recognised as a public health problem with substantial future economic implications for the national health and social care systems, understanding the context underlying the burden of obesity is necessary for the development of appropriate counter-strategies. DESIGN: We conducted a contextual analysis to explore factors that may have potentially contributed to the establishment of an obesogenic environment in Malta. A search of the literature published between 1990 and 2013 was conducted in MEDLINE and EMBASE. Twenty-two full-text articles were retrieved. Additional publications were identified following recommendations by Maltese public health experts; a review of relevant websites; and thorough hand searching of back issues of the Malta Medical Journal since 1990. SETTING: Malta. SUBJECTS: Whole population, with a focus on children. RESULTS: Results are organised and presented using the ANalysis Grid for Elements Linked to Obesity (ANGELO) framework. Physical, economic, policy and socio-cultural dimensions of the Maltese obesogenic environment are explored. CONCLUSIONS: Malta's obesity rates may be the result of an obesogenic environment characterised by limited infrastructure for active living combined with an energy-dense food supply. Further research is required to identify and quantify the strength of interactions between these potential environmental drivers of obesity in order to enable appropriate countermeasures to be developed
The mitochondrial Na+/Ca2+ exchanger upregulates glucose dependent Ca2+ signalling linked to insulin secretion.
Mitochondria mediate dual metabolic and Ca(2+) shuttling activities. While the former is required for Ca(2+) signalling linked to insulin secretion, the role of the latter in β cell function has not been well understood, primarily because the molecular identity of the mitochondrial Ca(2+) transporters were elusive and the selectivity of their inhibitors was questionable. This study focuses on NCLX, the recently discovered mitochondrial Na(+)/Ca(2+) exchanger that is linked to Ca(2+) signalling in MIN6 and primary β cells. Suppression either of NCLX expression, using a siRNA construct (siNCLX) or of its activity, by a dominant negative construct (dnNCLX), enhanced mitochondrial Ca(2+) influx and blocked efflux induced by glucose or by cell depolarization. In addition, NCLX regulated basal, but not glucose-dependent changes, in metabolic rate, mitochondrial membrane potential and mitochondrial resting Ca(2+). Importantly, NCLX controlled the rate and amplitude of cytosolic Ca(2+) changes induced by depolarization or high glucose, indicating that NCLX is a critical and rate limiting component in the cross talk between mitochondrial and plasma membrane Ca(2+) signalling. Finally, knockdown of NCLX expression was followed by a delay in glucose-dependent insulin secretion. These findings suggest that the mitochondrial Na(+)/Ca(2+) exchanger, NCLX, shapes glucose-dependent mitochondrial and cytosolic Ca(2+) signals thereby regulating the temporal pattern of insulin secretion in β cells
Modeling the growth of stylolites in sedimentary rocks
[1] Stylolites are ubiquitous pressure solution seams found in sedimentary rocks. Their morphology is shown to follow two self-affine regimes. Analyzing the scaling properties of their height over their average direction shows that (1) at small scale, they are self-affine surfaces with a Hurst exponent around 1, and (2) at large scale, they follow another self-affine scaling with Hurst exponent around 0.5. In the present paper, we show theoretically the influence of the main principal stress and the local geometry of the stylolitic interface on the dissolution reaction rate. We compute how it is affected by the deviation between the principal stress axis and the local interface between the rock and the soft material in the stylolite. The free energy entering in the dissolution reaction kinetics is expressed from the surface energy term and via integration from the stress perturbations due to these local misalignments. The resulting model shows the interface evolution at different stress conditions. In the stylolitic case, i.e., when the main principal stress is normal to the interface, two different stabilizing terms dominate at small and large scales which are linked respectively to the surface energy and to the elastic interactions. Integrating the presence of small-scale heterogeneities related to the rock properties of the grains in the model leads to the formulation of a Langevin equation predicting the dynamic evolution of the surface. This equation leads to saturated surfaces obeying the two observed scaling laws. Analytical and numerical analysis of this surface evolution model shows that the crossover length separating both scaling regimes depends directly on the applied far-field stress magnitude. This method gives the basis for the development of a paleostress magnitude marker. We apply the computation of this marker, i.e., the morphological analysis, on a stylolite found in the Dogger limestone layer located in the neighborhood of the ANDRA Underground Research Laboratory at Bure (eastern France). The results are consistent with the two scaling regimes expected, and the practical determination of the major principal paleostress, from the estimation of a crossover length, is illustrated on this example
Conformal Field Theory and the Alpha Space Transform
This thesis can be split into two parts. In the first, we expound the
alpha space formalism [1] and extend it beyond two dimensions. By performing a Sturm-Liouville analysis of the conformal quadratic Casimir differential equation, we define an invertible integral transform which maps functions on the Lorentzian square to alpha space. We explain how poles correspond to conformal blocks and provide numerous examples of interesting densities. After lifting the crossing equation to alpha space, we present a new representation of the accompanying kernel in terms of analytic Wilson functions. We also offer some comments on Regge physics
and analyticity. In the second, we investigate the perturbative renormalisation of deformed conformal field theories from the Hamiltonian perspective. We discuss the relation with conformal perturbation theory, to which we provide an explicit match up to third order in the coupling, and show how second-order anomalous dimensions in the Wilson-Fisher fixed points are straightforwardly computed in the Hamiltonian framework. We then focus on the cut-off employed in the truncated conformal space approach of Yurov and Zamolodchikov [2]. We discuss the appearance of
non-covariant and non-local counterterms to second order in the cut-off, explicitly in φ4 theory, and find a smooth cut-off to tame subleading oscillations
Investigating the Ways in Which Mobile Phone Images with Open-Source Data Can Be Used to Create an Augmented Virtual Environment (AVE)
This paper presents the development of an interactive system for constructing Augmented Virtual Environments (AVEs) by fusing mobile phone images with open-source geospatial data. By integrating 2D image data with 3D models derived from sources such as OpenStreetMap (OSM) and Digital Terrain Models (DTM), the proposed system generates immersive environments that enhance situational context. The system leverages Python for data processing and Unity for 3D visualization, interconnected via UDP-based two-way communication. Preliminary user evaluation demonstrates that the resulting AVEs accurately represent real-world scenes and improve users' contextual understanding. Key challenges addressed include projector calibration, precise model construction from heterogeneous data, and object detection for dynamic scene representation
Sibling relationships and family functioning in siblings of early adolescents, adolescents and young adults with autism spectrum disorder
The purpose of the study was to investigate how family functioning (defined as the ability that family members hold to manage stressful events, and intimate and social relationships), the degree to which family members feel happy and fulfilled with each other (called family satisfaction), and the demographical characteristics of siblings (age and gender) impacted on sibling relationships. The Circumplex Model of Marital and Family Systems and Behavioral Systems constituted the theoretical frameworks that guided our study. Eighty-six typically developing adolescents and young adults having a sister or a brother with autism spectrum disorder were enrolled. Results indicated that the youngest age group (early adolescents) reported to engage more frequently in negative behaviors with their siblings with ASD than the two older age groups (middle adolescents and young adults). No significant differences were found among the three age groups regarding behaviors derived from attachment, caregiving and affiliative systems. Family satisfaction and age significantly predicted behaviors during sibling interactions. Suggestions on prevention and intervention programs were discussed in order to prevent parentification among typically developing
siblings and decrease episodes of quarrels and overt conflicts between brothers and sisters with and without AS
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Gas-Particle Partitioning of Atmospheric Hg(II) and Its Effect on Global Mercury Deposition
Atmospheric deposition of Hg(II) represents a major input of mercury to surface environments. The phase of Hg(II) (gas or particle) has important implications for deposition. We use long-term observations of reactive gaseous mercury (RGM, the gaseous component of Hg(II)), particle-bound mercury (PBM, the particulate component of Hg(II)), fine particulate matter (PM2.5), and temperature (T) at five sites in North America to derive an empirical gas-particle partitioning relationship log10(K−1) = (10±1)–(2500±300)/T where K = (PBM/PM2.5)/RGM with PBM and RGM in common mixing ratio units, PM2.5 in μg m−3, and T in K. This relationship is within the range of previous work but is based on far more extensive data from multiple sites. We implement this empirical relationship in the GEOS-Chem global 3-D Hg model to partition Hg(II) between the gas and particle phases. The resulting gas-phase fraction of Hg(II) ranges from over 90 % in warm air with little aerosol to less than 10 % in cold air with high aerosol. Hg deposition to high latitudes increases because of more efficient scavenging of particulate Hg(II) by precipitating snow. Model comparison to Hg observations at the North American surface sites suggests that subsidence from the free troposphere (warm air, low aerosol) is a major factor driving the seasonality of RGM, while elevated PBM is mostly associated with high aerosol loads. Simulation of RGM and PBM at these sites is improved by including fast in-plume reduction of Hg(II) emitted from coal combustion and by assuming that anthropogenic particulate Hg(p) behaves as semi-volatile Hg(II) rather than as a refractory particulate component. We improve the simulation of Hg wet deposition fluxes in the US relative to a previous version of GEOS-Chem; this largely reflects independent improvement of the washout algorithm. The observed wintertime minimum in wet deposition fluxes is attributed to inefficient snow scavenging of gas-phase Hg(II).Earth and Planetary SciencesEngineering and Applied Science
Applications of alpha space
We extend the definition of ‘alpha space’ as introduced in [1] to two spacetime dimensions. We discuss how this can be used to find conformal block decompositions of known functions and how to easily recover several lightcone bootstrap results. In the second part of the paper we establish a connection between alpha space and the Lorentzian inversion formula of [2]
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