The Pioneer Anomaly

Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of the Newton's gravitational inverse-square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living Reviews in Relativit

Solving Nonlinear Parabolic Equations by a Strongly Implicit Finite-Difference Scheme

We discuss the numerical solution of nonlinear parabolic partial differential equations, exhibiting finite speed of propagation, via a strongly implicit finite-difference scheme with formal truncation error $\mathcal{O}\left[(\Delta x)^2 + (\Delta t)^2 \right]$. Our application of interest is the spreading of viscous gravity currents in the study of which these type of differential equations arise. Viscous gravity currents are low Reynolds number (viscous forces dominate inertial forces) flow phenomena in which a dense, viscous fluid displaces a lighter (usually immiscible) fluid. The fluids may be confined by the sidewalls of a channel or propagate in an unconfined two-dimensional (or axisymmetric three-dimensional) geometry. Under the lubrication approximation, the mathematical description of the spreading of these fluids reduces to solving the so-called thin-film equation for the current's shape $h(x,t)$. To solve such nonlinear parabolic equations we propose a finite-difference scheme based on the Crank--Nicolson idea. We implement the scheme for problems involving a single spatial coordinate (i.e., two-dimensional, axisymmetric or spherically-symmetric three-dimensional currents) on an equispaced but staggered grid. We benchmark the scheme against analytical solutions and highlight its strong numerical stability by specifically considering the spreading of non-Newtonian power-law fluids in a variable-width confined channel-like geometry (a "Hele-Shaw cell") subject to a given mass conservation/balance constraint. We show that this constraint can be implemented by re-expressing it as nonlinear flux boundary conditions on the domain's endpoints. Then, we show numerically that the scheme achieves its full second-order accuracy in space and time. We also highlight through numerical simulations how the proposed scheme accurately respects the mass conservation/balance constraint.Comment: 36 pages, 9 figures, Springer book class; v2 includes improvements and corrections; to appear as a contribution in "Applied Wave Mathematics II

Physical activity for people living with dementia: carer outcomes and side effects from the perspectives of professionals and family carers

Adherence to physical activity is challenging for people living with dementia, and largely dependent on carers' involvement. Carers are likely to support physical activity based on their perceived balance between benefits and potential side effects of such intervention for both patients and themselves. Professionals also have a role in terms of optimising such interventions not only for people with dementia but also their carers.publishe

The sugar and energy in non-carbonated sugar-sweetened beverages: a cross-sectional study.

BACKGROUND: The consumption of non-carbonated sugar-sweetened beverages (NCSSBs) has many adverse health effects. However, the sugar and energy content in NCSSBs sold in China remain unknown. We aimed to investigate the sugar and energy content of NCSSBs in China and how these contents were labelled. METHODS: A cross-sectional survey was conducted in 15 supermarkets in Haidian District, Beijing from July to October 2017. The product packaging and nutrient information panels of NCSSBs were recorded to obtain type of products (local/imported), serving size, nutrient contents of carbohydrate, sugar and energy. For those NCSSBs without sugar content information, we used carbohydrate content as a replacement. RESULTS: A total of 463 NCSSBs met the inclusion criteria and were included in our analysis. The median of sugar content and energy content was 9.6 [interquartile range (IQR): 7.1-11.3] g/100 ml and 176 (IQR: 121-201) kJ/100 ml. The median of sugar contents in juice drinks, tea-based beverages, sports drinks and energy drinks were 10.4, 8.5, 5.0 and 7.4 g/100 ml. Imported products had higher sugar and energy content than local products. There were 95.2% products of NCSSBs receiving a 'red'(high) label for sugars per portion according to the UK criteria, and 81.6% products exceeding the daily free sugar intake recommendation from the World Health Organization (25 g). There were 82 (17.7%) products with sugar content on the nutrition labels and 60.2% of them were imported products. CONCLUSIONS: NCSSBs had high sugar and energy content, and few of them provided sugar content information on their nutrition labels especially in local products. Measures including developing better regulation of labelling, reducing sugar content and restricting the serving size are needed for reducing sugar intakes in China

The yeast histidine protein kinase, Sln1p, mediates phosphotransfer to two response regulators, Ssk1p and Skn7p.

The Saccharomyces cerevisiae Sln1 protein is a 'two-component' regulator involved in osmotolerance. Two-component regulators are a family of signal-transduction molecules with histidine kinase activity common in prokaryotes and recently identified in eukaryotes. Phosphorylation of Sln1p inhibits the HOG1 MAP kinase osmosensing pathway via a phosphorelay mechanism including Ypd1p and the response regulator, Ssk1p. SLN1 also activates an MCM1-dependent reporter gene, P-lacZ, but this function is independent of Ssk1p. We present genetic and biochemical evidence that Skn7p is the response regulator for this alternative Sln1p signaling pathway. Thus, the yeast Sln1 phosphorelay is actually more complex than appreciated previously; the Sln1 kinase and Ypd1 phosphorelay intermediate regulate the activity of two distinct response regulators, Ssk1p and Skn7p. The established role of Skn7p in oxidative stress is independent of the conserved receiver domain aspartate, D427. In contrast, we show that Sln1p activation of Skn7p requires phosphorylation of D427. The expression of TRX2, previously shown to exhibit Skn7p-dependent oxidative-stress activation, is also regulated by the SLN1 phosphorelay functions of Skn7p. The identification of genes responsive to both classes of Skn7p function suggests a central role for Skn7p and the SLN1-SKN7 pathway in integrating and coordinating cellular response to various types of environmental stress

Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf

We evaluate the available palaeontological and geochemical proxy data from bivalves, bryozoans, silicoflagellates, diatoms and cetaceans for sea surface temperature (SST) regimes around the nearshore Antarctic coast during the late Neogene. These fossils can be found in a number of shallow marine sedimentary settings from three regions of the Antarctic continent, the northern Antarctic Peninsula, the Prydz Bay region and the western Ross Sea. Many of the proxies suggest maximum spring–summer SSTs that are warmer than present by up to 5 °C, which would result in reduced seasonal sea ice. The evidence suggests that the summers on the Antarctic shelf during the late Neogene experienced most of the warming, while winter SSTs were little changed from present. Feedbacks from changes in summer sea ice covermay have driven much of the lateNeogene ocean warming seen in stratigraphic records. Synthesized late Neogene and earliest Quaternary Antarctic shelf proxy data are compared to the multi-model SST estimates of the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Despite the fragmentary geographical and temporal context for the SST data, comparisons between the SSTwarming in each of the three regions represented in the marine palaeontological record of theAntarctic shelf and the PlioMIP climate simulations show a good concordance

Global leadership : key concepts and frameworks

This chapter provides an overview of key concepts and frameworks relating to global leadership. Spencer-Oatey starts by considering a range of definitions of leadership and then, drawing on those various definitions, argues that the enactment of leadership is a multiplex involving four key elements: leader, followers, purpose, and context. She explores each of these facets in turn, illustrating how they interact dynamically. She draws particular attention to the leader-follower relational dynamic and explains how Redeker et al’s (2014) leadership circumplex, which was used in case study data collection, can offer helpful insights. The chapter ends by considering the notion of global leadership and by touching on the various routes that people can take to develop into a global leader. Keywords: Defining leadership; leadership multiplex; leaders and followers; leaders and context/purpose; global leadershi