2,430 research outputs found

    Some Experiments on the Electrical Conductivity of Atmospheric Air

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    Change in interplanetary shock acceleration preceding STIP Interval 17

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    The intensity and frequency of shock acceleration events in the interplanetary medium decreased dramatically in early 1985. Low energy ions were observed by IMP 8 at 1 AU and Voyagers 1 and 2 at 22 and 16 AU, respectively. Voyager 1 was at 25 deg heliographic latitude while IMP 8 and Voyager 2 were near the solar equatorial plane. The decrease in low energy shock events led to a drop in the average ion flux by a factor of 20 to 50. It started about day 10 of 1985 in the approximately .5 MeV channel on IMP8 and took approximately 75 days to reach the new, lower, background level. The decrease at the Voyagers started approximately 50 days later. The time delay between the start of the decrease at IMP and at Voyager 2 implies that decrease was convected outward with a velocity of approximately 535 km/sec. The intensity and frequency of interplanetary shock events remained at the lower level for at least 1.5 years

    Links between parental life histories of wild salmon and the telomere lengths of their offspring

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    The importance of parental contributions to offspring development and subsequent performance is self-evident at a genomic level; however, parents can also affect offspring fitness by indirect genetic and environmental routes. The life history strategy that an individual adopts will be influenced by both genes and environment; and this may have important consequences for offspring. Recent research has linked telomere dynamics (i.e. telomere length and loss) in early life to future viability and longevity. Moreover, a number of studies have reported a heritable component to telomere length across a range of vertebrates, though the effects of other parental contribution pathways have been far less studied. By using wild Atlantic salmon with different parental life histories in an experimental split-brood IVF mating design and rearing the resulting families under standardised conditions, we show that there can be significant links between parental life history and offspring telomere length (studied at the embryo and fry stage). Maternal life history traits, in particular egg size, were most strongly related to offspring telomere length at the embryonic stage, but then became weaker through development. In contrast, paternal life history traits, such as the father's growth rate in early life, had a greater association in the later stages of offspring development. However, offspring telomere length was not significantly related to either maternal or paternal age at reproduction, nor to paternal sperm telomere length. This study demonstrates both the complexity and the importance of parental factors that can influence telomere length in early life

    Shorter juvenile telomere length is associated with higher survival to spawning in migratory Atlantic salmon

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    The risk of mortality associated with a long-distance migration will depend on an animal's physiological state, as well as the prevailing ecological conditions. Here we assess whether juvenile telomere length, which in endotherms has been shown to be a biomarker of physiological state and expected lifespan, predicts whether wild Atlantic salmon Salmo salar successfully complete their marine migration. Over 1800 juvenile fish were trapped, measured, PIT-tagged and a tissue biopsy taken when migrating as juveniles down-river towards the sea. Survivors of the marine phase of the life cycle were then re-trapped and re-sampled when returning to the river to spawn as sexually mature adults, 1.5-2.5 years later. Most individuals experienced a reduction in telomere length during the marine migratory phase of their life cycle. While the relative rate of telomere loss was greater in males than females, telomere loss was unrelated to growth at sea. Contrary to expectations, salmon that had the shortest telomeres at the time of the outward migration had the greatest probability of surviving through to the return migration. This effect, independent of body size, may indicate a trade-off between investment in readiness for marine life (which favours high glucocorticoid levels, known to increase telomere attrition in other vertebrate species) and investment in telomere maintenance. Survival was also significantly influenced by the seasonal timing of outward migration, with the fish migrating downstream earliest in the spring having the highest probability of return. This study reveals that telomere length is associated with survival, although in ways that contrast with patterns seen in endotherms. This illustrates that while telomeres may be universally important for chromosome protection, the potential for telomere dynamics to predict performance may vary across taxa

    Chapman-Enskog expansion about nonequilibrium states: the sheared granular fluid

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    The Chapman-Enskog method of solution of kinetic equations, such as the Boltzmann equation, is based on an expansion in gradients of the deviations fo the hydrodynamic fields from a uniform reference state (e.g., local equilibrium). This paper presents an extension of the method so as to allow for expansions about \emph{arbitrary}, far-from equilibrium reference states. The primary result is a set of hydrodynamic equations for studying variations from the arbitrary reference state which, unlike the usual Navier-Stokes hydrodynamics, does not restrict the reference state in any way. The method is illustrated by application to a sheared granular gas which cannot be studied using the usual Navier-Stokes hydrodynamics.Comment: 23 pages, no figures. Submited to PRE Replaced to correct misc. errors Replaced to correct misc. errors, make notation more consistant, extend discussio

    Settling Some Open Problems on 2-Player Symmetric Nash Equilibria

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    Over the years, researchers have studied the complexity of several decision versions of Nash equilibrium in (symmetric) two-player games (bimatrix games). To the best of our knowledge, the last remaining open problem of this sort is the following; it was stated by Papadimitriou in 2007: find a non-symmetric Nash equilibrium (NE) in a symmetric game. We show that this problem is NP-complete and the problem of counting the number of non-symmetric NE in a symmetric game is #P-complete. In 2005, Kannan and Theobald defined the "rank of a bimatrix game" represented by matrices (A, B) to be rank(A+B) and asked whether a NE can be computed in rank 1 games in polynomial time. Observe that the rank 0 case is precisely the zero sum case, for which a polynomial time algorithm follows from von Neumann's reduction of such games to linear programming. In 2011, Adsul et. al. obtained an algorithm for rank 1 games; however, it does not solve the case of symmetric rank 1 games. We resolve this problem

    Intra- and inter-operator variability of refractometric total proteins measurement of canine plasma

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    Refractometric total proteins are commonly used in practice as a quick and inexpensive way to measure total protein concentration in bodily fluids. Little information is available about how the operator performing the measurement affects the results. The aim of our study was to determine the inter- and intra-operator variability of refractometric total proteins measured on canine plasma using a temperature-compensated handheld refractometer. A pooled sample of canine lithium-heparin plasma was created using leftover samples from dogs presented to our hospital. The sample was then divided into three aliquots. Total proteins of these aliquots were measured by veterinary nurses, interns, residents and specialists working at our hospital. Statistical analysis revealed excellent inter-operator (ICC 0.99, CI 95% 0.971–1.00) and intra-operator (ICC 0.997, CI 95% 0.990–0.999) variability. Having different operators measuring refractometric total plasma proteins in practice should not affect the results. This suggests different operators can be used when monitoring total plasma proteins of a patient over time and when designing a study that involves this test

    Kinetic Theory of Response Functions for the Hard Sphere Granular Fluid

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    The response functions for small spatial perturbations of a homogeneous granular fluid have been described recently. In appropriate dimensionless variables, they have the form of stationary state time correlation functions. Here, these functions are expressed in terms of reduced single particle functions that are expected to obey a linear kinetic equation. The functional assumption required for such a kinetic equation, and a Markov approximation for its implementation are discussed. If, in addition, static velocity correlations are neglected, a granular fluid version of the linearized Enskog kinetic theory is obtained. The derivation makes no a priori limitation on the density, space and time scale, nor degree of inelasticity. As an illustration, recently derived Helfand and Green-Kubo expressions for the Navier-Stokes order transport coefficients are evaluated with this kinetic theory. The results are in agreement with those obtained from the Chapman-Enskog solution to the nonlinear Enskog kinetic equation.Comment: Submitted to J. Stat. Mec

    'It's complicated': reflections on teaching citizenship in Aotearoa New Zealand

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    The recently redesigned Massey University BA aims to produce responsible, world-conscious graduates who are active citizens, and who demonstrate a critical understanding of the peoples and cultures of 21st century Aotearoa New Zealand and the influences that have shaped them. The suite of compulsory core courses that emerged from this redesign process were developed before the university expressed a commitment to becoming Te Tiriti-led and were not explicitly designed with decolonisation in mind, but they ask questions and provoke reflection that we hope will contribute to decolonisation through the production of a cohort of graduates who have reflected on the multiple factors shaping their own identity, including New Zealand’s colonial past, can locate themselves in relation to global issues, and who have begun to think about questions of and possibilities for agency and action as citizens of ANZ and of the globe. These courses often unsettle indigenous and settler identities and relationships, and challenge student thinking about the rights and responsibilities they have at home and in the wider world. In this paper we reflect on the process of developing and teaching this course as a group of primarily settler / pākehā academics in conversation with Māori colleagues, and on our own learning through teaching. To do this we draw from our experiences and from research undertaken on the teaching of global citizenship in the core to interrogate our roles and responsibilities as academics in relation to decolonisation

    The Effect of a Sustained High-Fat Diet on the Metabolism of White and Brown Adipose Tissue and Its Impact on Insulin Resistance: A Selected Time Point Cross-Sectional Study.

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    (1) Background: studies on the long-term dynamic changes in fat depot metabolism in response to a high-fat diet (HFD) on hepatic lipid deposition and insulin resistance are sparse. This study investigated the dynamic changes produced by HFD and the production of dysfunctional fat depots on insulin resistance and liver lipid metabolism. (2) Methods: mice fed a chow or HFD (45% kcal fat) diet had three fat depots, liver, and blood collected at 6, 10, 20, and 30 weeks. Anthropometric changes and gene markers for adipogenesis, thermogenesis, ECM remodeling, inflammation, and tissue insulin resistance were measured. (3) Results: early responses to the HFD were increased body weight, minor deposition of lipid in liver, increased adipocyte size, and adipogenesis. Later changes were dysfunctional adipose depots, increased liver fat, insulin resistance (shown by changes in ITT) accompanied by increased inflammatory markers, increased fibrosis (fibrosis > 2-fold, p < 0.05 from week 6), and the presence of crown cells in white fat depots. Later, changes did not increase thermogenic markers in response to the increased calories and decreased UCP1 and PRDM16 proteins in WAT. (4) Conclusions: HFD feeding initially increased adipocyte diameter and number, but later changes caused adipose depots to become dysfunctional, restricting adipose tissue expansion, changing the brown/beige ratios in adipose depots, and causing ectopic lipid deposition and insulin resistance
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