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COVID-19 , Tromboembolia , Humanos , Tromboembolia/epidemiología , Tromboembolia/etiología , Sobrevivientes , Hospitales , Escocia/epidemiologíaAsunto(s)
COVID-19 , COVID-19/prevención & control , Hospitales , Humanos , Servicios de Información , Web Semántica , VacunaciónRESUMEN
Mars' sedimentary rock record preserves information on geological (and potential astrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars. A traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago. We report spatial differences in the mineralogy of time-equivalent sedimentary rocks <400 meters apart. These differences indicate localized infiltration of silica-poor brines, generated during deposition of overlying magnesium sulfate-bearing strata. We propose that destabilization of silicate minerals driven by silica-poor brines (rarely observed on Earth) was widespread on ancient Mars, because sulfate deposits are globally distributed.
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The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80-m stratigraphic interval. The mineralogy of the four samples is strongly influenced by aqueous alteration processes, including variations in water chemistries, redox, pH, and temperature. Localized hydrothermal events are evidenced by gray hematite and maturation of amorphous SiO2 to opal-CT. Low-temperature diagenetic events are associated with fluctuating lake levels, evaporative events, and groundwater infiltration. Among all mudstones analyzed in Gale crater, the diversity in diagenetic processes is primarily captured by the mineralogy and X-ray amorphous chemistry of the drilled rocks. Variations indicate a transition from magnetite to hematite and an increase in matrix-associated sulfates suggesting intensifying influence from oxic, diagenetic fluids upsection. Furthermore, diagenetic fluid pathways are shown to be strongly affected by unconformities and sedimentary transitions, as evidenced by the intensity of alteration inferred from the mineralogy of sediments sampled adjacent to stratigraphic contacts.
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In daily life, fast visual recognition of surrounding objects is facilitated through context-based expectations. However the ability to rapidly and accurately recognize unexpected stimuli in a given environment is also crucial and this ability is impaired with age. The present fMRI study aimed at comparing in young and older adults the neural correlates of fast object processing. Patterns of cerebral activity were investigated in response to briefly-presented (100 ms) congruent and incongruent natural scenes. Participants were slower and less accurate when categorizing objects in incongruent relative to congruent contexts. This behavioral cost was notably more pronounced in the older group. Height and multivariate patterns of fMRI activity in context-selective regions were equivalent in both age groups, suggesting preserved processing of coarse scene features in older participants. Incongruent scenes elicited additional activity in the parahippocampal gyrus that possibly reflected simultaneous activation of rarely co-occurring neural representations. Contextual effects were observed in object-selective cortex for the young group only, and may be driven by detection of mismatch between actually perceived and previously-experienced associations. In the older group exclusively, increased bilateral prefrontal and left fusiform activity in response to incongruent scenes was observed. However this supplemental activity was not found to efficiently contribute to improve task performance in difficult visual conditions. Altogether these results suggest age-related changes in the interaction between object- and context-processing pathways, that may subserve impairment in fast identification of unexpected objects in natural scenes.
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Envejecimiento/fisiología , Asociación , Corteza Cerebral/fisiología , Reconocimiento Visual de Modelos/fisiología , Desempeño Psicomotor/fisiología , Reconocimiento en Psicología/fisiología , Adulto , Factores de Edad , Anciano , Corteza Cerebral/diagnóstico por imagen , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Giro Parahipocampal/diagnóstico por imagen , Giro Parahipocampal/fisiología , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/fisiología , Factores de Tiempo , Adulto JovenRESUMEN
[This corrects the article DOI: 10.1371/journal.pcbi.1004568.].
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Jamming occurs when objects like grains are packed tightly together (e.g. grain silos). It is highly cooperative and can lead to phenomena like earthquakes, traffic jams, etc. In this paper we point out the paramount importance of the underlying contact network for jammed systems; the network must have one contact in excess of isostaticity and a finite bulk modulus. Isostatic means that the number of degrees of freedom is exactly balanced by the number of constraints. This defines a large class of networks that can be constructed without the necessity of packing particles together compressively (either in the lab or computationally). One such construction, which we explore here, involves setting up the Delaunay triangulation of a Poisson disk sampling and then removing edges to maximize the bulk modulus until the isostatic plus one edge is reached. This construction works in any dimensions and here we give results in 2D where we also show how such networks can be transformed into disk packs.
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Verifying that a face is from a target person (e.g. finding someone in the crowd) is a critical ability of the human face processing system. Yet how fast this can be performed is unknown. The 'entry-level shift due to expertise' hypothesis suggests that - since humans are face experts - processing faces should be as fast - or even faster - at the individual than at superordinate levels. In contrast, the 'superordinate advantage' hypothesis suggests that faces are processed from coarse to fine, so that the opposite pattern should be observed. To clarify this debate, three different face processing levels were compared: (1) a superordinate face categorization level (i.e. detecting human faces among animal faces), (2) a face familiarity level (i.e. recognizing famous faces among unfamiliar ones) and (3) verifying that a face is from a target person, our condition of interest. The minimal speed at which faces can be categorized (â¼260ms) or recognized as familiar (â¼360ms) has largely been documented in previous studies, and thus provides boundaries to compare our condition of interest to. Twenty-seven participants were included. The recent Speed and Accuracy Boosting procedure paradigm (SAB) was used since it constrains participants to use their fastest strategy. Stimuli were presented either upright or inverted. Results revealed that verifying that a face is from a target person (minimal RT at â¼260ms) was remarkably fast but longer than the face categorization level (â¼240ms) and was more sensitive to face inversion. In contrast, it was much faster than recognizing a face as familiar (â¼380ms), a level severely affected by face inversion. Face recognition corresponding to finding a specific person in a crowd thus appears achievable in only a quarter of a second. In favor of the 'superordinate advantage' hypothesis or coarse-to-fine account of the face visual hierarchy, these results suggest a graded engagement of the face processing system across processing levels as reflected by the face inversion effects. Furthermore, they underline how verifying that a face is from a target person and detecting a face as familiar - both often referred to as "Face Recognition" - in fact differs.
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Reconocimiento Facial , Reconocimiento en Psicología , Adulto , Femenino , Humanos , Masculino , Tiempo de Reacción , Factores de Tiempo , Adulto JovenRESUMEN
The 'taste of food' plays an important role in food choice. Furthermore, foods high in fat, sugar and salt are highly palatable and associated with increased food consumption. Research exploring taste importance on dietary choice, behaviour and intake is limited, particularly in young adults. Therefore, in this study a total of 1306 Australian university students completed questionnaires assessing dietary behaviors (such as how important taste was on food choice) and frequency of food consumption over the prior month. Diet quality was also assessed using a dietary guideline index. Participants had a mean age of 20 ± 5 years, Body Mass Index (BMI) of 22 ± 3 kg/m(2), 79% were female and 84% Australian. Taste was rated as being a very or extremely important factor for food choice by 82% of participants. Participants who rated taste as highly important, had a poorer diet quality (p = 0.001) and were more likely to consume less fruit (p = 0.03) and vegetables (p = 0.05). Furthermore, they were significantly more likely to consume foods high in fat, sugar and salt, including chocolate and confectionary, cakes and puddings, sweet pastries, biscuits, meat pies, pizza, hot chips, potato chips, takeaway meals, soft drink, cordial and fruit juice (p = 0.001-0.02). They were also more likely to consider avoiding adding salt to cooking (p = 0.02) and adding sugar to tea or coffee (p = 0.01) as less important for health. These findings suggest that the importance individuals place on taste plays an important role in influencing food choice, dietary behaviors and intake.
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Conducta de Elección , Dieta Saludable , Dieta Occidental/efectos adversos , Conducta Alimentaria , Preferencias Alimentarias , Conocimientos, Actitudes y Práctica en Salud , Cooperación del Paciente , Adolescente , Adulto , Estudios de Cohortes , Estudios Transversales , Dieta Saludable/etnología , Dieta Occidental/etnología , Conducta Alimentaria/etnología , Femenino , Preferencias Alimentarias/etnología , Conocimientos, Actitudes y Práctica en Salud/etnología , Humanos , Masculino , Encuestas Nutricionales , Ciencias de la Nutrición/educación , Cooperación del Paciente/etnología , Sensación , Estudiantes , Gusto , Universidades , Victoria , Adulto JovenRESUMEN
We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.
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STUDY QUESTION: How do counsellors facilitating known 'open' embryo donation (ED) experience their roles and responsibilities? SUMMARY ANSWER: Counsellors regard counselling for ED as entailing significant responsibility to ensure that the longer-term implications of the practice are understood and that positive relationships are established that will promote the well-being of donors, recipients, their families and the children involved. WHAT IS KNOWN ALREADY: While counselling is frequently recommended in third-party assisted reproduction, there has been little research into the experiences of counsellors and their perceptions of their roles and responsibilities. STUDY DESIGN, SIZE, DURATION: Fertility counsellors were interviewed between March and October 2012 as to their experiences and perceptions of their roles and responsibilities. PARTICIPANTS/MATERIALS, SETTING, METHODS: Fertility counsellors were recruited from across New Zealand and interviews were conducted with all nine counsellors involved in ED counselling. Interview data were analysed thematically to identify main themes. MAIN RESULTS AND THE ROLE OF CHANCE: Counsellors regard ED as a complex practice with enduring implications arising from the genetic link between donors and offspring, which is seen to bestow immutable social ties. They see their role as the provision of implications counselling and the facilitation of ongoing positive relationships between donors and recipients in an 'open' context. Counsellors express concern about their responsibility for promoting the welfare of all parties--including that of the child--the limitations of counselling, and the conflation of assessment and counselling roles. LIMITATIONS, REASONS FOR CAUTION: Experiences of counselling for ED may change over time as longer-term outcomes become more apparent. WIDER IMPLICATIONS OF THE FINDINGS: Further consideration needs to be given as to how the welfare principle may best be operationalised in counselling practice, particularly in contexts of 'open' donation. STUDY FUNDING/COMPETING INTERESTS: This study was funded by an AUT University Faculty of Health and Environmental Sciences research grant. The authors have no conflicts of interest to declare.
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Consejo , Destinación del Embrión/psicología , Familia/psicología , Técnicas Reproductivas Asistidas/psicología , Donantes de Tejidos/psicología , Adulto , Niño , Revelación , Femenino , Humanos , Masculino , Nueva Zelanda , RolRESUMEN
Finite pieces of locally isostatic networks have a large number of floppy modes because of missing constraints at the surface. Here we show that by imposing suitable boundary conditions at the surface the network can be rendered effectively isostatic. We refer to these as anchored boundary conditions. An important example is formed by a two-dimensional network of corner sharing triangles, which is the focus of this paper. Another way of rendering such networks isostatic is by adding an external wire along which all unpinned vertices can slide (sliding boundary conditions). This approach also allows for the incorporation of boundaries associated with internal holes and complex sample geometries, which are illustrated with examples. The recent synthesis of bilayers of vitreous silica has provided impetus for this work. Experimental results from the imaging of finite pieces at the atomic level need such boundary conditions, if the observed structure is to be computer refined so that the interior atoms have the perception of being in an infinite isostatic environment.
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The most successful protein structure prediction methods to date have been template-based modeling (TBM) or homology modeling, which predicts protein structure based on experimental structures. These high accuracy predictions sometimes retain structural errors due to incorrect templates or a lack of accurate templates in the case of low sequence similarity, making these structures inadequate in drug-design studies or molecular dynamics simulations. We have developed a new physics based approach to the protein refinement problem by mimicking the mechanism of chaperons that rehabilitate misfolded proteins. The template structure is unfolded by selectively (targeted) pulling on different portions of the protein using the geometric based technique FRODA, and then refolded using hierarchically restrained replica exchange molecular dynamics simulations (hr-REMD). FRODA unfolding is used to create a diverse set of topologies for surveying near native-like structures from a template and to provide a set of persistent contacts to be employed during re-folding. We have tested our approach on 13 previous CASP targets and observed that this method of folding an ensemble of partially unfolded structures, through the hierarchical addition of contact restraints (that is, first local and then nonlocal interactions), leads to a refolding of the structure along with refinement in most cases (12/13). Although this approach yields refined models through advancement in sampling, the task of blind selection of the best refined models still needs to be solved. Overall, the method can be useful for improved sampling for low resolution models where certain of the portions of the structure are incorrectly modeled.
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Modelos Moleculares , Replegamiento Proteico , Desplegamiento Proteico , Proteínas/química , Simulación de Dinámica MolecularRESUMEN
Diverse classes of proteins function through large-scale conformational changes and various sophisticated computational algorithms have been proposed to enhance sampling of these macromolecular transition paths. Because such paths are curves in a high-dimensional space, it has been difficult to quantitatively compare multiple paths, a necessary prerequisite to, for instance, assess the quality of different algorithms. We introduce a method named Path Similarity Analysis (PSA) that enables us to quantify the similarity between two arbitrary paths and extract the atomic-scale determinants responsible for their differences. PSA utilizes the full information available in 3N-dimensional configuration space trajectories by employing the Hausdorff or Fréchet metrics (adopted from computational geometry) to quantify the degree of similarity between piecewise-linear curves. It thus completely avoids relying on projections into low dimensional spaces, as used in traditional approaches. To elucidate the principles of PSA, we quantified the effect of path roughness induced by thermal fluctuations using a toy model system. Using, as an example, the closed-to-open transitions of the enzyme adenylate kinase (AdK) in its substrate-free form, we compared a range of protein transition path-generating algorithms. Molecular dynamics-based dynamic importance sampling (DIMS) MD and targeted MD (TMD) and the purely geometric FRODA (Framework Rigidity Optimized Dynamics Algorithm) were tested along with seven other methods publicly available on servers, including several based on the popular elastic network model (ENM). PSA with clustering revealed that paths produced by a given method are more similar to each other than to those from another method and, for instance, that the ENM-based methods produced relatively similar paths. PSA applied to ensembles of DIMS MD and FRODA trajectories of the conformational transition of diphtheria toxin, a particularly challenging example. For the AdK transition, the new concept of a Hausdorff-pair map enabled us to extract the molecular structural determinants responsible for differences in pathways, namely a set of conserved salt bridges whose charge-charge interactions are fully modelled in DIMS MD but not in FRODA. PSA has the potential to enhance our understanding of transition path sampling methods, validate them, and to provide a new approach to analyzing conformational transitions.
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Modelos Químicos , Modelos Moleculares , Complejos Multiproteicos/química , Complejos Multiproteicos/ultraestructura , Proteínas/química , Proteínas/ultraestructura , Algoritmos , Simulación por Computador , Movimiento (Física) , Conformación ProteicaRESUMEN
STUDY QUESTION: How do embryo donors and recipients understand and experience embryo donation (ED)? SUMMARY ANSWER: Donors and recipients regard the genetic link between donors and donor-conceived child as significant, and draw on metaphors of ED as adoption and as building extended family networks in order to manage the complex interplay of genetic, gestational and social aspects of reproduction and family-building. WHAT IS KNOWN ALREADY: The uptake of embryo donation internationally is relatively low and there has been little research into the outcomes and experiences of ED for donor and recipient families. STUDY DESIGN, SIZE, DURATION: Embryo donors and recipients in New Zealand were interviewed between March and October 2012 as to their understandings and experiences of embryo donation. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were recruited from across New Zealand and interviews were conducted with 22 donors (10 couples, 2 individuals) and 15 recipients (5 couples, 5 individuals). Interview data were analysed thematically to identify factors that influenced their perspectives and affected their experiences. MAIN RESULTS AND THE ROLE OF CHANCE: The genetic link between donors and offspring is regarded as bestowing immutable social ties by both donors and recipients. This makes ED a difficult choice for both donors, who experience a sense of ongoing responsibility for offspring welfare, and for recipients, who may have concerns about the donor-offspring bond. Disclosure of genetic background is regarded as critical for the welfare of both the donor-conceived child as well as siblings in the donor family. Both donors and recipients draw parallels between ED and open adoption practices, and draw on extended family constructs in order to describe their relationship to each other. LIMITATIONS, REASONS FOR CAUTION: Donors and recipients were interviewed at various stages of the ED process, and experiences may change over time. WIDER IMPLICATIONS OF THE FINDINGS: The comparison of ED with open adoption practice and the metaphor of extended family-building both help make sense of and complicate the ED experience. These concepts help to structure expectations for the assessment for ED, the disclosure of donor conception, and the nature of relationships, information-exchange and contact. STUDY FUNDING/COMPETING INTERESTS: This study was funded by an AUT University Faculty of Health Environmental Sciences research grant.
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Destinación del Embrión/ética , Destinación del Embrión/psicología , Técnicas Reproductivas Asistidas/ética , Técnicas Reproductivas Asistidas/psicología , Donantes de Tejidos/psicología , Adopción , Actitud Frente a la Salud , Revelación , Composición Familiar , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Nueva Zelanda , Responsabilidad Parental , Embarazo , HermanosRESUMEN
We reveal significant qualitative differences in the rigidity transition of three types of disordered network materials: randomly diluted spring networks, jammed sphere packings, and stress-relieved networks that are diluted using a protocol that avoids the appearance of floppy regions. The marginal state of jammed and stress-relieved networks are globally isostatic, while marginal randomly diluted networks show both overconstrained and underconstrained regions. When a single bond is added to or removed from these isostatic systems, jammed networks become globally overconstrained or floppy, whereas the effect on stress-relieved networks is more local and limited. These differences are also reflected in the linear elastic properties and point to the highly effective and unusual role of global self-organization in jammed sphere packings.
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Modelos Teóricos , Algoritmos , Biopolímeros/química , ElasticidadRESUMEN
The recent synthesis and characterisation of bilayers of vitreous silica has produced valuable new information on ring sizes and distributions. In this paper, we compare the ring statistics of experimental samples with computer generated samples. The average ring size is fixed at six by topology, but the width, skewness and other moments of the distribution of ring edges are characteristics of particular samples. We examine the Aboav-Weaire law that quantifies the propensity of smaller rings to be adjacent to larger rings, and find similar results for available experimental samples which however differ somewhat from computer-generated bilayers. We introduce a new law for the areas of rings of various sizes.
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We summarize results for two exactly soluble classes of bond-diluted models for rigidity percolation, which can serve as a benchmark for numerical and approximate methods. For bond dilution problems involving rigidity, the number of floppy modes F plays the role of a free energy. Both models involve pathological lattices with two-dimensional vector displacements. The first model involves hierarchical lattices where renormalization group calculations can be used to give exact solutions. Algebraic scaling transformations produce a transition of the second order, with an unstable critical point and associated scaling laws at a mean coordination
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Vibrational spectra of proteins potentially give insight into biologically significant molecular motion and the proportions of different types of secondary structure. Vibrational spectra can be calculated either from normal modes obtained by diagonalizing the mass-weighted Hessian or from the time autocorrelation function derived from molecular dynamics trajectories. The Hessian matrix is calculated from force fields because it is not practical to calculate the Hessian from quantum mechanics for large molecules. As an alternative to molecular dynamics the spectral response can be calculated from a time autocorrelation derived from numerical solution of the harmonic equations of motion, resulting in calculations at least 4 times faster. Because the calculation also scales linearly with number of atoms, N, it is faster than normal-mode calculations that scale as N (3) for proteins with more then 4,700 atoms. Using this method it is practical to perform all-atom calculations for large biological systems, for example viral capsids, with the order of 10(5) atoms.