Local Time Asymmetry of Saturn\u27s Magnetosheath Flows

Using gross averages of the azimuthal component of flow in Saturn\u27s magnetosheath, we find that flows in the prenoon sector reach a maximum value of roughly half that of the postnoon side. Corotational magnetodisc plasma creates a much larger flow shear with solar wind plasma prenoon than postnoon. Maxwell stress tensor analysis shows that momentum can be transferred out of the magnetosphere along tangential field lines if a normal component to the boundary is present, i.e., field lines which pierce the magnetopause. A Kelvin‐Helmholtz unstable flow gives rise to precisely this situation, as intermittent reconnection allows the magnetic field to thread the boundary. We interpret the Kelvin‐Helmholtz instability acting along the magnetopause as a tangetial drag, facilitating two‐way transport of momentum through the boundary. We use reduced magnetosheath flows in the dawn sector as evidence of the importance of this interaction in Saturn\u27s magnetosphere

Ultrasonography and color Doppler of proximal gluteal enthesitis in juvenile idiopathic arthritis: a descriptive study

Background: The presence of enthesitis (insertional inflammation) in patients with juvenile idiopathic arthritis (JIA) is difficult to establish clinically and may influence classification and treatment of the disease. We used ultrasonography (US) and color Doppler (CD) imaging to detect enthesitis at the small and deep-seated proximal insertion of the gluteus medius fascia on the posterior iliac crest where clinical diagnosis is difficult. The findings in JIA patients were compared with those obtained in healthy controls and with the patients' MRI results. Methods: Seventy-six proximal gluteus medius insertions were studied clinically (tenderness to palpation of the posterior iliac crest) and by US and CD (echogenicity, thickness, hyperemia) in 38 patients with JIA and in 38 healthy controls, respectively (median age 13 years, range 7-18 years). In addition, an additional MRI examination of the sacroiliac joints and iliac crests was performed in all patients. Results: In patients with focal, palpable tenderness, US detected decreased echogenicity of the entheses in 53% of the iliac crests (bilateral in 37% and unilateral in 32%). US also revealed significantly thicker entheses in JIA patients compared to healthy controls (p < 0.003 left side, p < 0.001 right side). There was no significant difference in thickness between the left and right sides in individual subjects. Hyperemia was detected by CD in 37% (28/76) of the iliac crests and by contrast-enhanced MRI in 12% (6/50). Conclusions: According to US, the gluteus medius insertion was thicker in JIA patients than in controls, and it was hypoechoic (enthesitis) in about half of the patients. These findings may represent chronic, inactive disease in some of the patients, because there was only limited Doppler flow and MRI contrast enhancement. The present study indicates that US can be useful as an adjunct to clinical examination for improved assessment of enthesitis in JIA. This may influence disease classification, ambition to treat, and choice of treatment regimen

Sustained lobe reconnection in Saturn’s magnetotail

The degree to which solar wind driving may affect Saturn’s magnetosphere is not yet fully understood. We present observations that suggest that under some conditions the solar wind does govern the character of the plasma sheet in Saturn’s outer magnetosphere. On 16 September 2006, the Cassini spacecraft, at a radial distance of 37 Rs near local midnight, observed a sunward flowing ion population for ~5 h, which was accompanied by enhanced Saturn Kilometric Radiation emissions. We interpret this beam as the outflow from a long‐lasting episode of Dungey‐type reconnection, i.e., reconnection of previously open flux containing magnetosheath material. The beam occurred in the middle of a several‐day interval of SKR activity and enhanced lobe magnetic field strength, apparently caused by the arrival of a solar wind compression region with significantly higher than average dynamic pressure. The arrival of the high‐pressure solar wind also marked a change in the composition of the plasma‐sheet plasma, from water‐group‐dominated material clearly of inner‐magnetosphere origin to material dominated by light‐ion composition, consistent with captured magnetosheath plasma. This event suggests that under the influence of prolonged high solar wind dynamic pressure, the tail plasma sheet, which normally consists of inner‐magnetospheric plasma, is eroded away by ongoing reconnection that then involves open lobe field lines. This process removes open magnetic flux from the lobes and creates a more Earth‐like, Dungey‐style outer plasma sheet dominantly of solar wind origin. This behavior is potentially a recurrent phenomenon driven by repeating high‐pressure streams (corotating interaction regions) in the solar wind, which also drive geomagnetic storms at Earth.Key PointsEvidence for long‐lasting Dungey‐type magnetotail reconnection at Saturn is presentedThis event is associated with arrival of a solar wind stream‐driven compression regionCreation of a more Earth‐like outer plasma sheet may be a recurrent stream‐driven phenomenonPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134869/1/jgra52237.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134869/2/jgra52237_am.pd

The Roles of Flux Tube Entropy and Effective Gravity in the Inward Plasma Transport at Saturn

The inward plasma transport at the Saturnian magnetosphere is examined using the flux tube interchange stability formalism developed by Southwood & Kivelson. Seven events are selected. Three cases are considered: (1) the injected flux tube and ambient plasmas are nonisotropic, (2) the injected flux tube and ambient plasmas are isotropic, and (3) the injected flux tube plasma is isotropic, but the ambient plasma is nonisotropic. Case 1 may be relevant for fresh injections, while case 3 may be relevant for old injections. For cases 1 and 2, all but one event have negative stability conditions, suggesting that the flux tube should be moving inward. For case 3, the injections located at L \u3e 11 have negative stability conditions, while four out of five of the injections at L \u3c 9 have positive stability conditions. The positive stability condition for small L suggests that the injection may be near its equilibrium position and possibly oscillating thereabouts-hence the outward transport if the flux tube overshot the equilibrium position. The flux tube entropy plays an important role in braking the plasma inward transport. When the stability condition is positive, it is because the entropy term, which is positive, counters and dominates the effective gravity term, which is negative for all the events. The ambient plasma and drift-out from adjacent injections can affect the stability and the inward motion of the injected flux tube. The results have implications for inward plasma transport in the Jovian magnetosphere, as well as other fast-rotating planetary magnetospheres

Polaritons in an electron gas—quasiparticles and landau effective interactions

Two-dimensional semiconductors inside optical microcavities have emerged as a versatile platform to explore new hybrid light–matter quantum states. A strong light–matter coupling leads to the formation of exciton-polaritons, which in turn interact with the surrounding electron gas to form quasiparticles called polaron-polaritons. Here, we develop a general microscopic framework to calculate the properties of these quasiparticles, such as their energy and the interactions between them. From this, we give microscopic expressions for the parameters entering a Landau theory for the polaron-polaritons, which offers a simple yet powerful way to describe such interacting light–matter many-body systems. As an example of the application of our framework, we then use the ladder approximation to explore the properties of the polaron-polaritons. Furthermore, we show that they can be measured in a non-demolition way via the light transmission/reflection spectrum of the system. Finally, we demonstrate that the Landau effective interaction mediated by electron-hole excitations is attractive leading to red shifts of the polaron-polaritons. Our work provides a systematic framework to study exciton-polaritons in electronically doped two-dimensional materials such as novel van der Waals heterostructures.</jats:p

Trends in cow numbers and culling rate in the Irish cattle population, 2003 to 2006

Cows are the main economic production units of Ireland's cattle industry. Therefore, demographic information, including overall numbers and survival rates, are relevant to the Irish agricultural industry. However, few data are available on the demographics of cows within a national population, either in Ireland or elsewhere, despite the recent development of comprehensive national cattle databases in many EU Member States. This study has sought: to determine the rate of cow culling from the national herd; to determine the rate of culling by type (dairy, beef), age, method of exit, date of exit and interval between last calving and exit; to calculate the national cow on-farm mortality rate; and to compare the Irish rates with published data from other countries. This work was conducted using data recorded in the national Cattle Movement Monitoring System (CMMS). Culling refers to the exit of cows from the national herd, as a result of death but regardless of reason, and cow-culling rate was calculated as the number of cow exits (as defined above) each year divided by the number of calf births in the same year. Culling rate was determined by type (dairy or beef), date of birth, method of exit (slaughter or on-farm death), month of exit and interval between last calving and exit. The average cow-culling rate during 2003 to 2006 was 19.6% (21.3% for dairy, 18% for beef). While comparisons must be treated with caution, it concluded that the overall rates of culling in Ireland fell within published internationally accepted norms. The on-farm mortality rate of 3.2-4.1% was similar to that reported in comparable studies

Experimental Analysis of Nonlinear Impairments in Fibre Optic Transmission Systems up to 7.3 THz

An effective way of increasing the overall optical fibre capacity is by expanding the bandwidth used to transmit signals. In this paper, the impact of expanding the transmission bandwidth on the optical communication system is experimentally studied using the achievable rates as a performance metric. The trade-offs between the use of larger bandwidths and higher nonlinear interference (NLI) noise is experimentally and theoretically analysed. The growth of NLI noise is investigated for spectral bandwidths from 40 GHz up to 7.3 THz using 64-QAM and Nyquist pulse-shaping. Experimental results are shown to be in line with the predictions from the Gaussian-Noise model showing a logarithmic growth in NLI noise as the signal bandwidth is extended. A reduction of the information rate of only 10 % was found between linear and non-linear transmission across several transmission bandwidths, increasing up to 7.3 THz. Finally, the power transfer between channels due to stimulated Raman scattering effect is analysed showing up to 2 dB power tilt at optimum power for the largest transmitted bandwidth of 7.3 THz

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand

Distances from Surface Brightness Fluctuations

The practice of measuring galaxy distances from their spatial fluctuations in surface brightness is now a decade old. While several past articles have included some review material, this is the first intended as a comprehensive review of the surface brightness fluctuation (SBF) method. The method is conceptually quite simple, the basic idea being that nearby (but unresolved) star clusters and galaxies appear "bumpy", while more distant ones appear smooth. This is quantified via a measurement of the amplitude of the Poisson fluctuations in the number of unresolved stars encompassed by a CCD pixel (usually in an image of an elliptical galaxy). Here, we describe the technical details and difficulties involved in making SBF measurements, discuss theoretical and empirical calibrations of the method, and review the numerous applications of the method from the ground and space, in the optical and near-infrared. We include discussions of stellar population effects and the "universality" of the SBF standard candle. A final section considers the future of the method.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 22 pages, including 3 postscript figures; uses Kluwer's crckapb.sty LaTex macro file, enclose

Spontaneous and deliberate future thinking: A dual process account

© 2019 Springer Nature.This is the final published version of an article published in Psychological Research, licensed under a Creative Commons Attri-bution 4.0 International License. Available online at: https://doi.org/10.1007/s00426-019-01262-7.In this article, we address an apparent paradox in the literature on mental time travel and mind-wandering: How is it possible that future thinking is both constructive, yet often experienced as occurring spontaneously? We identify and describe two ‘routes’ whereby episodic future thoughts are brought to consciousness, with each of the ‘routes’ being associated with separable cognitive processes and functions. Voluntary future thinking relies on controlled, deliberate and slow cognitive processing. The other, termed involuntary or spontaneous future thinking, relies on automatic processes that allows ‘fully-fledged’ episodic future thoughts to freely come to mind, often triggered by internal or external cues. To unravel the paradox, we propose that the majority of spontaneous future thoughts are ‘pre-made’ (i.e., each spontaneous future thought is a re-iteration of a previously constructed future event), and therefore based on simple, well-understood, memory processes. We also propose that the pre-made hypothesis explains why spontaneous future thoughts occur rapidly, are similar to involuntary memories, and predominantly about upcoming tasks and goals. We also raise the possibility that spontaneous future thinking is the default mode of imagining the future. This dual process approach complements and extends standard theoretical approaches that emphasise constructive simulation, and outlines novel opportunities for researchers examining voluntary and spontaneous forms of future thinking.Peer reviewe