190 research outputs found

    Physics of Neutron Star Crusts

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    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

    Sources of avoidance motivation: Valence effects from physical effort and mental rotation

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    When reaching goals, organisms must simultaneously meet the overarching goal of conserving energy. According to the law of least effort, organisms will select the means associated with the least effort. The mechanisms underlying this bias remain unknown. One hypothesis is that organisms come to avoid situations associated with unnecessary effort by generating a negative valence toward the stimuli associated with such situations. Accordingly, merely using a dysfunctional, ‘slow’ computer mouse causes participants to dislike ambient neutral images (Study 1). In Study 2, nonsense shapes were liked less when associated with effortful processing (135° of mental rotation) versus easier processing (45° of rotation). Complementing ‘fluency’ effects found in perceptuo-semantic research, valence emerged from action-related processing in a principled fashion. The findings imply that negative valence associations may underlie avoidance motivations, and have practical implications for educational/workplace contexts in which effort and positive affect are conducive to success

    Changes over time in the effect of marital status on cancer survival

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    <p>Abstract</p> <p>Background</p> <p>Rates of all-cause and cause-specific mortality are higher among unmarried than married individuals. Cancer survival is also poorer in the unmarried population. Recently, some studies have found that the excess all-cause mortality of the unmarried has increased over time, and the same pattern has been shown for some specific causes of death. The objective of this study was to investigate whether there has been a similar change over time in marital status differences in cancer survival.</p> <p>Methods</p> <p>Discrete-time hazard regression models for cancer deaths among more than 440 000 women and men diagnosed with cancer 1970-2007 at age 30-89 were estimated, using register data encompassing the entire Norwegian population. More than 200 000 cancer deaths during over 2 million person-years of exposure were analyzed.</p> <p>Results</p> <p>The excess mortality of the never-married compared to the married has increased steadily for men, in particular the elderly. Among elderly women, the excess mortality of the never-married compared to the married has increased, and there are indications of an increasing excess mortality of the widowed. The excess mortality of divorced men and women, however, has been stable.</p> <p>Conclusions</p> <p>There is no obvious explanation for the increasing disadvantage among the never-married. It could be due to a relatively poorer general health at time of diagnosis, either because of a more protective effect of partnership in a society that may have become less cohesive or because of more positive selection into marriage. Alternatively, it could be related to increasing differentials with respect to treatment. Today's complex cancer therapy regimens may be more difficult for never-married to follow, and health care interventions directed and adapted more specifically to the broad subgroup of never-married patients might be warranted.</p

    Effect of Supplementation with Zinc and Other Micronutrients on Malaria in Tanzanian Children: A Randomised Trial

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    Hans Verhoef and colleagues report findings from a randomized trial conducted among Tanzanian children at high risk for malaria. Children in the trial received either daily oral supplementation with either zinc alone, multi-nutrients without zinc, multi-nutrients with zinc, or placebo. The investigators did not find evidence from this study that zinc or multi-nutrients protected against malaria episodes

    Reoccurring patterns in hierarchical protein materials and music: The power of analogies

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    Complex hierarchical structures composed of simple nanoscale building blocks form the basis of most biological materials. Here we demonstrate how analogies between seemingly different fields enable the understanding of general principles by which functional properties in hierarchical systems emerge, similar to an analogy learning process. Specifically, natural hierarchical materials like spider silk exhibit properties comparable to classical music in terms of their hierarchical structure and function. As a comparative tool here we apply hierarchical ontology logs (olog) that follow a rigorous mathematical formulation based on category theory to provide an insightful system representation by expressing knowledge in a conceptual map. We explain the process of analogy creation, draw connections at several levels of hierarchy and identify similar patterns that govern the structure of the hierarchical systems silk and music and discuss the impact of the derived analogy for nanotechnology.Comment: 13 pages, 3 figure

    Anemia of Inflammation Is Related to Cognitive Impairment among Children in Leyte, The Philippines

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    Past studies have demonstrated that iron deficiency anemia is related to deficits in cognitive fucntioning in children, and treating iron deficiency anemia with iron supplementation can improve cognition. Anemia of inflammation is another type of anemia caused by many diseases of lesser-developed countries including bacterial and parasitic infections. Anemia of inflammation is characterized by disordered iron metabolism, such that iron is sequestered in storage forms, preventing its use from tissues that require it. We hypothesized that decreased iron delivery to the brain in the context of anemia of inflammation might lead to decreased cognitive performance. This study found that children with anemia of inflammation had decreased cognitive performance in specific domains, compared to subjects with no anemia. True total body iron deficiency anemia was related to lower performance in the same domains. The only treatment option for anemia of inflammation is treatment of the underlying disease. Iron supplementation will not prevent cognitive deficits in children with anemia of inflammation. Interventions aimed towards maximizing the cognitive development of children in lesser-developed countries will need to focus on the prevention and treatment of bacterial and parasitic infections

    Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut

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    Fish larval development, not least the spectacular process of flatfish metamorphosis, appears to be under complex endocrine control, many aspects of which are still not fully elucidated. In order to obtain data on the functional development of two major endocrine glands, the pituitary and the thyroid, during flatfish metamorphosis, histology, immunohistochemistry and in situ hybridization techniques were applied on larvae of the Atlantic halibut (Hippoglossus hippoglossus), a large, marine flatfish species, from hatching through metamorphosis. The material was obtained from a commercial hatchery. Larval age is defined as day-degrees (D =accumulated daily temperature from hatching). Sporadic thyroid follicles are first detected in larvae at 142 D (27 days post-hatch), prior to the completion of yolk sack absorption. Both the number and activity of the follicles increase markedly after yolk sack absorption and continue to do so during subsequent development. The larval triiodothyronine (T3) and thyroxine (T4) content increases, subsequent to yolk absorption, and coincides with the proliferation of thyroid follicles. A second increase of both T3 and T4 occurs around the start of metamorphosis and the T3 content further increases at the metamorphic climax. Overall, the T3 content is lower than T4. The pituitary gland can first be distinguished as a separate organ at the yolk sack stage. During subsequent development, the gland becomes more elongated and differentiates into neurohypophysis (NH), pars distalis (PD) and pars intermedia (PI). The first sporadic endocrine pituitary cells are observed at the yolk sack stage, somatotrophs (growth hormone producing cells) and somatolactotrophs (somatolactin producing cells) are first observed at 121 D (23 days post-hatch), and lactotrophs (prolactin producing cells) at 134 D (25 days post-hatch). Scarce thyrotrophs are evident after detection of the first thyroid follicles (142 D ), but coincident with a phase in which follicle number and activity increase (260 D ). The somatotrophs are clustered in the medium ventral region of the PD, lactotrophs in the anterior part of the PD and somatolactotrophs are scattered in the mid and posterior region of the pituitary. At around 600 D , coinciding with the start of metamorphosis, somatolactotrophs are restricted to the interdigitating tissue of the NH. During larval development, the pituitary endocrine cells become more numerous. The present data on thyroid development support the notion that thyroid hormones may play a significant role in Atlantic halibut metamorphosis. The time of appearance and the subsequent proliferation of pituitary somatotrophs, lactotrophs, somatolactotrophs and thyrotrophs indicate at which stages of larval development and metamorphosis these endocrine cells may start to play active regulatory roles.This work has been carried out within the projects ‘‘Endocrine Control as a Determinant of Larval Quality in Fish Aquaculture’’ (CT-96-1422) and ‘‘Arrested development: The Molecular and Endocrine Basis of Flatfish Metamorphosis’’ (Q5RS-2002-01192), with financial support from the Commission of the European Communities. However, it does not necessarily reflect the Commission’s views and in no way anticipates its future policy in this area. This project was further supported by the Swedish Council for Agricultural and Forestry Research and Pluriannual funding to CCMAR by the Portuguese Science and Technology Council

    Gemini-LIGHTS: Herbig Ae/Be and massive T-Tauri protoplanetary disks imaged with Gemini Planet Imager

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    This is the final version. Available on open access from the American Astronomical Society via the DOI in this recordWe present the complete sample of protoplanetary disks from the Gemini- Large Imaging with GPI Herbig/T-tauri Survey (Gemini-LIGHTS) which observed bright Herbig Ae/Be stars and T-Tauri stars in near-infrared polarized light to search for signatures of disk evolution and ongoing planet formation. The 44 targets were chosen based on their near- and mid-infrared colors, with roughly equal numbers of transitional, pre-transitional, and full disks. Our approach explicitly did not favor well-known, “famous” disks or those observed by ALMA, resulting in a less-biased sample suitable to probe the major stages of disk evolution during planet formation. Our optimized data reduction allowed polarized flux as low as 0.002% of the stellar light to be detected, and we report polarized scattered light around 80% of our targets. We detected point-like companions for 47% of the targets, including 3 brown dwarfs (2 confirmed, 1 new), and a new super-Jupiter mass candidate around V1295 Aql. We searched for correlations between the polarized flux and system parameters, finding a few clear trends: presence of a companion drastically reduces the polarized flux levels, far-IR excess correlates with polarized flux for non-binary systems, and systems hosting disks with ring structures have stellar masses < 3 M . Our sample also included four hot, dusty “FS CMa” systems and we detected large-scale (> 100 au) scattered light around each, signs of extreme youth for these enigmatic systems. Science-ready images are publicly available through multiple distribution channels using a new FITS file standard jointly developed with members of the VLT/SPHERE team.NSFEuropean Research Council (ERC)ANI

    Using role-play to improve students’ confidence and perceptions of communication in a simulated volcanic crisis

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    Traditional teaching of volcanic science typically emphasises scientific principles and tends to omit the key roles, responsibilities, protocols, and communication needs that accompany volcanic crises. This chapter provides a foundation in instructional communication, education, and risk and crisis communication research that identifies the need for authentic challenges in higher education to challenge learners and provide opportunities to practice crisis communication in real-time. We present an authentic, immersive role-play called the Volcanic Hazards Simulation that is an example of a teaching resource designed to match professional competencies. The role-play engages students in volcanic crisis concepts while simultaneously improving their confidence and perceptions of communicating science. During the role-play, students assume authentic roles and responsibilities of professionals and communicate through interdisciplinary team discussions, media releases, and press conferences. We characterised and measured the students’ confidence and perceptions of volcanic crisis communication using a mixed methods research design to determine if the role-play was effective at improving these qualities. Results showed that there was a statistically significant improvement in both communication confidence and perceptions of science communication. The exercise was most effective in transforming low-confidence and low-perception students, with some negative changes measured for our higher-learners. Additionally, students reported a comprehensive and diverse set of best practices but focussed primarily on the mechanics of science communication delivery. This curriculum is a successful example of how to improve students’ communication confidence and perceptions
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