Observations of high-latitude geomagnetic field fluctuations during St. Patrick's Day storm: Swarm and SuperDARN measurements

The aim of this work is to study the properties of the magnetic field's fluctuations produced by ionospheric and magnetospheric electric currents during the St. Patrick's Day geomagnetic storm (17 March 2015). We analyse the scaling features of the external contribution to the horizontal geomagnetic field recorded simultaneously by the three satellites of the Swarm constellation during a period of 13 days (13–25 March 2015). We examine the different latitudinal structure of the geomagnetic field fluctuations and analyse the dynamical changes in the magnetic field scaling features during the development of the geomagnetic storm. Analysis reveals consistent patterns in the scaling properties of magnetic fluctuations and striking changes between the situation before the storm, during the main phase and recovery phase. We discuss these dynamical changes in relation to those of the overall ionospheric polar convection and potential structures as reconstructed using SuperDARN data. Our findings suggest that distinct turbulent regimes characterised the mesoscale magnetic field's fluctuations and that some factors, which are known to influence large-scale fluctuations, have also an influence on mesoscale fluctuations. The obtained results are an example of the capability of geomagnetic field fluctuations data to provide new insights about ionospheric dynamics and ionosphere–magnetosphere coupling. At the same time, these results could open doors for development of new applications where the dynamical changes in the scaling features of the magnetic fluctuations are used as local indicators of magnetospheric conditions

Effects of Abrupt Variations of Solar Wind Dynamic Pressure on the High-Latitude Ionosphere

We show the results of a statistical study on the effects in the high-latitude ionosphere of abrupt variations of solar wind dynamic pressure, using Super Dual Auroral Radar Network (SuperDARN) data in both hemispheres. We find that, during periods of quiet ionospheric conditions, the amount of radar backscatter increases when a variation in the dynamic pressure occurs, both positive (increase of the pressure) and negative (decrease of the pressure). We also investigate the behaviour of the Cross-Polar Cap Potential (CPCP) during pressure variations and show preliminary results

STATISTICS OF THE VELOCITY GRADIENT TENSOR IN SPACE PLASMA TURBULENT FLOWS

In the last decade, significant advances have been presented for the theoretical characterization and experimental techniques used to measure and model all of the components of the velocity gradient tensor in the framework of fluid turbulence. Here, we attempt the evaluation of the small-scale velocity gradient tensor for a case study of space plasma turbulence, observed in the Earth's magnetosheath region by the CLUSTER mission. In detail, we investigate the joint statistics P(R, Q) of the velocity gradient geometric invariants R and Q, and find that this P(R, Q) is similar to that of the low end of the inertial range for fluid turbulence, with a pronounced increase in the statistics along the so-called Vieillefosse tail. In the context of hydrodynamics, this result is referred to as the dissipation/dissipation-production due to vortex stretching

Observations of the relationship between ionospheric central polar cap and dayside throat convection velocities, and solar wind/IMF driving

Convection observations from the Southern Hemisphere Super Dual Auroral Radar Network are presented and examined for their relationship to solar wind and interplanetary magnetic field (IMF) conditions, restricted to periods of steady IMF. Analysis is concentrated on two specific regions, the central polar cap and the dayside throat region. An example time series is discussed in detail with specific examples of apparent direct control of the convection velocity by the solar wind driver. Closer examination, however, shows that there is variability in the flows that cannot be explained by the driving. Scatterplots and histograms of observations from all periods in the year 2013 that met the selection criteria are given and their dependence on solar wind driving is examined. It is found that on average the flow velocity depends on the square root of the rate of flux entry to the polar cap. It is also found that there is a large level of variability that is not strongly related to the solar wind driving

The role of cross-over bypass graft in the treatment of acute ischaemia of the lower limb

Introduction. The Authors reports their experience with the use of femoro-femoral cross-over bypass graft in the management of acute lower limb ischaemia. Patients and methods. Fourteen femoro-femoral bypass graft were performed for acute lower limb ischaemia due to unilateral thrombosis of iliac and femoral artery in 8 cases, late unilateral occlusion of a branch of previous aortobifemoral bypass in 3 cases, acute thrombosis of abdominal aorta in 2 cases and in the last one for an injury of common iliac artery during urological procedure. In all the cases the operations were carried out under local anaesthesia and a subcutaneous bypass with “C” shape type configuration with 8 mm Dacron prosthesis were performed. The first and second year primary and secondary patency rates and limb salvage rates were evaluated. Results. One and two year patency rate was 83.3 (10/12) and 70% (7/10) respectively. Secondary patency rate and limb salvage rate was 91.6% (11/12) and 80% (8/10) respectively. A tight amputation had to performed in 3 failed reconstruction (3/12, 25%). Two patient died within 30 days after surgery from acute myocardial infarct. In 1 case infection occurred and re-do femorofemoral cross-over bypass with saphenous vein was carried out (8.3%). Conclusions. Cross-over bypass is an attractive technique, especially in case of acute ischemia because of its simplicity, low morbidity and mortality, and good long term results

CLOCK gene polymorphisms and quality of aging in a cohort of nonagenarians – The MUGELLO Study

Abstract A total of 356 elderly subjects [257F; 88–106 years] were genotyped for three polymorphisms of the CLOCK gene by TaqMan real-time PCR approach, in order to find associations with quality of aging. Subjects homozygous for the minor allele of rs1801260 were less frequently overweight (p = 0.046), had higher fasting glucose levels (p = 0.037), better scores at the Clock Drawing Test (CDT) (p = 0.047) and worse scores at the Geriatric Depression Scale (p = 0.032). Subjects homozygous for the minor allele of rs11932595 showed higher fasting glucose levels (p = 0.044) and better scores at CDT (p = 0.030). Conversely, subjects homozygous for the minor allele of rs4580704 showed higher triglyceride (p = 0.012), and LDL-cholesterol levels (p = 0.44), and a greater adherence to the Mediterranean diet (MD) (p = 0.044). In addition, AAC, AAG, GGC and AGC (rs1801260–rs11932595–rs4580704) haplotypes were analyzed: AAG was associated with higher risk of overweight (p = 0.008), hypertriglyceridemia (p = 0.040) and hypercholesterolemia (p = 0.036); GGC with lower risk of hyperglycemia (p = 0.022), better sleep pattern (p = 0.001) and with better score at mini-mental state examination (p = 0.010); AGC with lower risk of depression (p = 0.026) and AAC with lower adherence to the MD (p = 0.028). Therefore, CLOCK gene polymorphisms let us hypothesize an involvement in the quality of aging in a cohort of nonagenarians

Occurrence of F region echoes for the polar cap SuperDARN radars

Observations by six Super Dual Auroral Radar Network (SuperDARN) polar cap radars, three in the northern hemisphere and three in the southern hemispheres, are considered to assess F region echo occurrence rates over solar, season, and day cycles and to establish relationship between the echo occurrence rate and the background electron density and plasma flow velocity magnitude. The echo occurrence rate is shown to increase toward the solar cycle maximum, more distinctly on the nightside, consistent with a general trend of the background electron density. Over the last 5 years, the echo occurrence rates decline at a rate of 5-10% per year. The pattern of seasonal and diurnal variations in echo occurrence is found to be consistent with previous SuperDARN publications. Minor dips in echo occurrence rate are observed in winter solstices, and these are related to an overall decrease in the electron density. In most of the time sectors, the echo occurrence rate increases with the electron density but only up to a certain threshold value after which the dependence saturates. The level of the saturation depends on season, local time, and average plasma flow velocity magnitude. For the summer daytime observations, the echo occurrence rate correlates with variations of both electron density and plasma flow velocity magnitude

On the Scaling Properties of Magnetic-field Fluctuations through the Inner Heliosphere

Although the interplanetary magnetic-field variability has been extensively investigated in situ using data from several space missions, newly launched missions providing high-resolution measures and approaching the Sun offer the possibility to study the multiscale variability in the innermost solar system. Here, using Parker Solar Probe measurements, we investigate the scaling properties of solar wind magnetic-field fluctuations at different heliocentric distances. The results show a clear transition at distances close to say 0.4 au. Closer to the Sun fluctuations show a f-3/2 frequency power spectra and regular scaling properties, while for distances larger than 0.4 au fluctuations show a Kolmogorov spectrum f-5/3 and are characterized by anomalous scalings. The observed statistical properties of turbulence suggest that the solar wind magnetic fluctuations, in the late stage far from the Sun, show a multifractal behavior typical of turbulence and described by intermittency, while in the early stage, when leaving the solar corona, a breakdown of these properties is observed, thus showing a statistical monofractal global self-similarity. Physically, the breakdown observed close to the Sun should be due either to a turbulence with regular statistics or to the presence of intense stochastic fluctuations able to cancel out the correlations necessary for the presence of anomalous scaling

Upgrades of the ESPERTA forecast tool for solar proton events

The Empirical model for Solar Proton Events Real Time Alert (ESPERTA) exploits three solar parameters (flare longitude, soft X-ray fluence, and radio fluence) to provide a timely prediction for the occurrence of solar proton events (SPEs, i.e., when the >10MeV proton flux is ≥10 pfu) after the emission of a ≥M2 flare. In addition, it makes a prediction for the most dangerous SPEs for which the >10 MeV proton flux is ≥100 pfu. In this paper, we study two different ways to upgrade the ESPERTA model and implement it in real time: 1) by using ground based observations from the LOFAR stations; 2) by applying a novel machine learning algorithm to flare-based parameters to provide early warnings of SPE occurrence together with a fine-tuned radiation storm level. As a last step, we perform a preliminary study using a neural network to forecast the proton flux 1-hour ahead to complement the ESPERTA tool. We evaluate the models over flare and SPE data covering the last two solar cycles and discuss their performance, limits, and advantages