Kinetic Signatures and Intermittent Turbulence in the Solar Wind Plasma

A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 AU. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are non-uniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.Comment: 4 pages, 3 figures, submitted to Physical Review Letter

Film thickness measurements in a running hydrostatic unit using ultrasound

The present paper describes the measurement of the oil film thickness in the range of a few micrometers in an operating hydrostatic unit using ultrasound. The investigated tribological system consists of a rotating steel cylinder block and a stationary bi-metal valve plate under static and hydrodynamic lubrication. The film thickness has been recorded in a wide range of operating conditions, pressure between 100 to 300 bar and rotational speed between 500 and 3000 rpm, to support a deeper understanding of the system. Temperature sensors were implemented next to the ultrasound sensors to compensate the ultrasound signal amplitude and phase change due to temperature dependent acoustic impedances. To confirm the results, especially the presence of deliberate zero-film conditions, wear profiles of the running surface were taken. The ultrasound technique also allows the real-time observation of film thickness oscillations with shaft and piston frequency. Steady-state measurements confirm the system behavior observed in transient operation and zero-film conditions with respect to hardware configuration were detected. The findings will be utilized to support current product development activities and to validate and improve simulation models used for film thickness predictions

Legionella bozemanii , an Elusive Agent of Fatal Cavitary Pneumonia

Abstract : A 67-year-old patient died of Legionella bozemanii pneumonia with negative urinary antigen and negative serology. Cystic lesions in pneumonia of unknown origin should lead to the differential diagnosis of L. bozemanii infection

A nonextensive entropy approach to solar wind intermittency

The probability distributions (PDFs) of the differences of any physical variable in the intermittent, turbulent interplanetary medium are scale dependent. Strong non-Gaussianity of solar wind fluctuations applies for short time-lag spacecraft observations, corresponding to small-scale spatial separations, whereas for large scales the differences turn into a Gaussian normal distribution. These characteristics were hitherto described in the context of the log-normal, the Castaing distribution or the shell model. On the other hand, a possible explanation for nonlocality in turbulence is offered within the context of nonextensive entropy generalization by a recently introduced bi-kappa distribution, generating through a convolution of a negative-kappa core and positive-kappa halo pronounced non-Gaussian structures. The PDFs of solar wind scalar field differences are computed from WIND and ACE data for different time lags and compared with the characteristics of the theoretical bi-kappa functional, well representing the overall scale dependence of the spatial solar wind intermittency. The observed PDF characteristics for increased spatial scales are manifest in the theoretical distribution functional by enhancing the only tuning parameter $\kappa$, measuring the degree of nonextensivity where the large-scale Gaussian is approached for $\kappa \to \infty$. The nonextensive approach assures for experimental studies of solar wind intermittency independence from influence of a priori model assumptions. It is argued that the intermittency of the turbulent fluctuations should be related physically to the nonextensive character of the interplanetary medium counting for nonlocal interactions via the entropy generalization.Comment: 17 pages, 7 figures, accepted for publication in Astrophys.

Life-threatening orolingual angioedema during thrombolysis in acute ischemic stroke

Background: Orolingual angioedema can occur during thrombolysis with alteplase in stroke patients. However, data about its frequency, severity and the significance of concurrent use of angiotensin-converting-enzyme inhibitors (ACEi) are sparse. Objective: (1), to alert to the potentially life-threatening complication of orolingual angioedema. (2), to present CT-scans of the tongue which exclude lingual hematoma. (3), to estimate the frequency of orolingual angioedema. (4), to evaluate the risk associated with the concurrent use of ACEi. Methods: Single center, databank-based observational study on 120 consecutive patients with i. v. alteplase for acute stroke. Meta-analysis of all stroke studies on alteplase-associated angioedema, which provided detailed information about the use of ACEinhibitors. Across studies, the Peto odds ratio of orolingual angioedema for "concurrent use of ACEi" was calculated. Results: Orolingual angioedema occurred in 2 of 120 patients (1.7%, 95% CI 0.2-5.9 %).Angioedema was mild in one, but rapidly progressive in another patient. Impending asphyxia prompted immediate intubation. CT showed orolingual swelling but no bleeding. One of 19 (5%) patients taking ACEi had orolingual angioedema, compared to 1 of 101 (1%) patients without ACEi. Medline search identified one further study about the occurrence of alteplase-associated angioedema in stroke patients stratified to the use of ACEi. Peto odds ratio of 37 (95 % CI 8-171) indicated an increased risk of alteplasetriggered angioedema for patients with ACEi (p <0.001). Conclusion: Orolingual angioedema is a potentially life-threatening complication of alteplase treatment in stroke patients, especially in those with ACEi. Orolingual hematoma as differential diagnosis can be excluded by CT-sca

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established

Partial joint processing with efficient backhauling using particle swarm optimization

In cellular communication systems with frequency reuse factor of one, user terminals (UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount of required feedback. However, it is difficult to achieve a corresponding reduction on the backhaul related to the precoding weights, when a linear zero forcing beamforming technique is used. In this work, particle swarm optimization is proposed as a tool to design the precoding weights under feedback and backhaul constraints related to PJP. The precoder obtained with the objective of weighted interference minimization allows some multiuser interference in the system, and it is shown to improve the sum rate by 66% compared to a conventional zero forcing approach, for those users experiencing low signal to interference plus noise ratio

Coronal heating distribution due to low-frequency wave-driven turbulence

The heating of the lower solar corona is examined using numerical simulations and theoretical models of magnetohydrodynamic turbulence in open magnetic regions. A turbulent energy cascade to small length scales perpendicular to the mean magnetic field can be sustained by driving with low-frequency Alfven waves reflected from mean density and magnetic field gradients. This mechanism deposits energy efficiently in the lower corona, and we show that the spatial distribution of the heating is determined by the mean density through the Alfven speed profile. This provides a robust heating mechanism that can explain observed high coronal temperatures and accounts for the significant heating (per unit volume) distribution below two solar radius needed in models of the origin of the solar wind. The obtained heating per unit mass on the other hand is much more extended indicating that the heating on a per particle basis persists throughout all the lower coronal region considered here.Comment: 19 pages, 5 figures. Accepted for publication in Ap

Roles of Fast-Cyclotron and Alfven-Cyclotron Waves for the Multi-Ion Solar Wind

Using linear Vlasov theory of plasma waves and quasi-linear theory of resonant wave-particle interaction, the dispersion relations and the electromagnetic field fluctuations of fast and Alfven waves are studied for a low-beta multi-ion plasma in the inner corona. Their probable roles in heating and accelerating the solar wind via Landau and cyclotron resonances are quantified. We assume that (1) low-frequency Alfven and fast waves have the same spectral shape and the same amplitude of power spectral density; (2) these waves eventually reach ion cyclotron frequencies due to a turbulence cascade; (3) kinetic wave-particle interaction powers the solar wind. The existence of alpha particles in a dominant proton/electron plasma can trigger linear mode conversion between oblique fast-whistler and hybrid alpha-proton cyclotron waves. The fast-cyclotron waves undergo both alpha and proton cyclotron resonances. The alpha cyclotron resonance in fast-cyclotron waves is much stronger than that in Alfven-cyclotron waves. For alpha cyclotron resonance, an oblique fast-cyclotron wave has a larger left-handed electric field fluctuation, a smaller wave number, a larger local wave amplitude, and a greater energization capability than a corresponding Alfven-cyclotron wave at the same wave propagation angle \theta, particularly at $80^\circ$ < \theta < $90^\circ$. When Alfven-cyclotron or fast-cyclotron waves are present, alpha particles are the chief energy recipient. The transition of preferential energization from alpha particles to protons may be self-modulated by differential speed and temperature anisotropy of alpha particles via the self-consistently evolving wave-particle interaction. Therefore, fast-cyclotron waves as a result of linear mode coupling is a potentially important mechanism for preferential energization of minor ions in the main acceleration region of the solar wind.Comment: 29 pages, 10 figures, 3 tables. Accepted for publication in Solar Physic

Inter-occurrence Times in the Bak-Tang-Wiesenfeld Sandpile Model: A Comparison with the Turbulent Statistics of Solar Flares

A sequence of bursts observed in an intermittent time series may be caused by a single avalanche, even though these bursts appear as distinct events when noise and/or instrument resolution impose a detection threshold. In the Bak-Tang-Wiesenfeld sandpile, the statistics of quiet times between bursts switches from Poissonian to scale invariant on raising the threshold for detecting instantaneous activity, since each zero-threshold avalanche breaks into a hierarchy of correlated bursts. Calibrating the model with the time resolution of GOES data, qualitative agreement with the inter-occurrence time statistics of solar flares at different intensity thresholds is found.Comment: 4 page