The interaction between transpolar arcs and cusp spots

Transpolar arcs and cusp spots are both auroral phenomena which occur when the interplanetary magnetic field is northward. Transpolar arcs are associated with magnetic reconnection in the magnetotail, which closes magnetic flux and results in a “wedge” of closed flux which remains trapped, embedded in the magnetotail lobe. The cusp spot is an indicator of lobe reconnection at the high-latitude magnetopause; in its simplest case, lobe reconnection redistributes open flux without resulting in any net change in the open flux content of the magnetosphere. We present observations of the two phenomena interacting—i.e., a transpolar arc intersecting a cusp spot during part of its lifetime. The significance of this observation is that lobe reconnection can have the effect of opening closed magnetotail flux. We argue that such events should not be rare

Stationary strings near a higher-dimensional rotating black hole

We study stationary string configurations in a space-time of a higher-dimensional rotating black hole. We demonstrate that the Nambu-Goto equations for a stationary string in the 5D Myers-Perry metric allow a separation of variables. We present these equations in the first-order form and study their properties. We prove that the only stationary string configuration which crosses the infinite red-shift surface and remains regular there is a principal Killing string. A worldsheet of such a string is generated by a principal null geodesic and a timelike at infinity Killing vector field. We obtain principal Killing string solutions in the Myers-Perry metrics with an arbitrary number of dimensions. It is shown that due to the interaction of a string with a rotating black hole there is an angular momentum transfer from the black hole to the string. We calculate the rate of this transfer in a spacetime with an arbitrary number of dimensions. This effect slows down the rotation of the black hole. We discuss possible final stationary configurations of a rotating black hole interacting with a string.Comment: 13 pages, contains additianal material at the end of Section 8, also small misprints are correcte

UPGRO Hidden Crisis Research consortium: unravelling past failures for future success in rural water supply: initial project approach for assessing rural water supply functionality and levels of performance

The new Sustainable Development Goals (SDGs) set a much stronger focus on sustainability and performance of water services, and have highly ambitious goals to achieve universal access to safe and reliable water for all by 2030 (UN 2013 ). Poor functionality of water points threatens to undermine progress, and a lack of knowledge for the reasons behind this make it difficult to recommend improvements and take corrective action. As a first step it is necessary to be able to reliably monitor current rates of functionality and to have a clear benchmark as to what constitutes a functional water point. Currently, there is no single accepted definition for functionality, although organisations are working towards this as a means of tracking progress towards the SDGs. This report sets out the initial work by the Hidden Crisis project to develop a framework approach to assess functionality in terms of different levels of performance, and a set of standard indicators which can be used to assess functionality. The report presents the results of a literature review examining the following questions: (1) what are the current approaches to defining functionality of hand-pump boreholes; and (2) what are the robust standards by which the functionality of a HPB, or population of HPB’s, can be assessed. From analyses of the literature we have developed preliminary guidelines and applied these to develop a preliminary framework

Root and Sucrose Yields of Sugarbeets as Affected by Mid-to-Late-Season Water Stress

Investigations of the irrigation water requirement of sugarbeets (Beta vulgaris L.) in Arizona and California have shown that water stress several weeks before harvest of fall-planted beets reduces root yields but increases sucrose concentration (2,3). Their studies showed that, since soil and plant water stress late in the season did not significantly reduce sucrose production, irrigations could be discontinued 3 to 4 weeks before harvest for maximum water economy. Mid- to late-season water deficit studies on spring-planted sugarbeets at this Center in 1977 and 1978 clearly showed that sucrose yield was reduced very little in this area, if at all, if irrigations were discontinued after the soil profile was filled with water about 1 August or 10 to 12 weeks before harvest, on soil having a useable soil water reservoir of at least 200 mm (1) . However, if no rainfall occurs, a light irrigation about 1 month after water cutoff may be advantageous. The major difference between these two areas (Arizona-California and Idaho) is that in Arizona and California, potential evapotranspiration rates are higher and increasing when fall-planted beets are harvested; whereas in Idaho, potential rates are lower and decreasing when spring-planted beets are harvested. Allowing mid- to late-season water stress to develop in the Idaho area reduces irrigation water requirements by about 30% during August, September, and October when irrigation water and hydro-electric power for pumping are in shortest supply. Other recent investigations also show the drought tolerance of sugarbeets throughout the growing season ( 8, 11)

Entropy of Lovelock Black Holes

A general formula for the entropy of stationary black holes in Lovelock gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.Comment: 15 pages, plain Latex, NSF-ITP-93-4

No Go Theorem for Kinematic Self-Similarity with A Polytropic Equation of State

We have investigated spherically symmetric spacetimes which contain a perfect fluid obeying the polytropic equation of state and admit a kinematic self-similar vector of the second kind which is neither parallel nor orthogonal to the fluid flow. We have assumed two kinds of polytropic equations of state and shown in general relativity that such spacetimes must be vacuum.Comment: 5 pages, no figures. Revtex. One word added to the title. Final version to appear in Physical Review D as a Brief Repor

A hidden crisis: strengthening the evidence base on the sustainability of rural groundwater supplies: results from a pilot study in Uganda

Extending and sustaining access to rural water supplies remains central to improving the health and livelihoods of poor people, particularly women, in Africa, where 400 million rural inhabitants have no form of utility provided water, and universal access to water hinges on accelerated development of groundwater (UN 2013). The ‘future proofing’ of groundwater investments is therefore vital, especially in the context of global and local trends including demographic shifts, environmental impacts of human activity and climate change (Taylor et al. 2013). The emphasis, in recent years, on accelerating access to new infrastructure has obscured a hidden crisis of failure. More than 30% of sources are non‐functional within a few years of construction (Rietveld et al. 2009, RWSN 2009, Lockwood et al. 2011) and a greater number are seasonal (for example 50% in Sierra Leone) (MoEWR 2012). The accumulated costs to governments, donors, and, above all, rural people, are enormous. The original benefits generated by the new infrastructure – improved health, nutrition, time savings, education, particularly for the poorest – are lost if improved services cannot be sustained. The cumulative effect of rural water supply failure in Africa over the past 20 years has been estimated by the World Bank to represent a lost investment in excess of $1.2 billion. Critically, there is limited data or analysis on why sources are non‐functional and therefore little opportunity to learn from past mistakes. This report provides a summary of the work undertaken by the UK‐funded UPGro research programme ('Unlocking the Potential for Groundwater for the Poor') for sub‐Saharan Africa (SSA) funded by the Natural Environment Research Council (NERC), the Economic and Social Research Council (ESRC) and the Department for International Development (DfID). The Catalyst Grant project ‘A Hidden Crisis’ was aimed at developing a methodology and toolbox to investigate the causes of failure in groundwater‐based water services in SSA, which could form the foundation for more substantial and larger‐scale research in the future to develop a statistically significant evidence base to examine water point functionality and the underlying causes of failure across a range of physical, social, institutional and governance environments in SSA. To test the toolbox and methodology developed, a pilot study was conducted in northeast Uganda Overall, the approach and methods developed in the catalyst project have been shown to make a significant step towards developing a replicable and robust methodology which can be used to generate a systematic evidence base for supply failure. The work has gone a significant way to encapsulating the complexity of the interlinked aspects of the problem, balancing the natural science and engineering (“technical”) aspects of the research with those concerning the ability of communities to manage and maintain their water points (the “social” aspects). The multiplicity of interlinked causes of water point failure was explicitly acknowledged and taken into account through the use of multi‐disciplinary field and analytical methods within the toolbox and in selection of the research team. The multi‐disciplinary methods of investigation used were highly practical and appropriate to the information sought, and based on detailed observational science

A boundary value problem for the five-dimensional stationary rotating black holes

We study the boundary value problem for the stationary rotating black hole solutions to the five-dimensional vacuum Einstein equation. Assuming the two commuting rotational symmetry and the sphericity of the horizon topology, we show that the black hole is uniquely characterized by the mass, and a pair of the angular momenta.Comment: 16 pages, no figure