Persistent enhancement of the HF pump-induced plasma line measured with a UHF diagnostic radar at HAARP

Plasma lines excited by a powerful, high-frequency (HF) radio wave are studied using data obtained with an ultrahigh frequency (UHF) radar at HAARP (High Frequency Active Auroral Research Program) from 3 to 5 February 2005. Of particular interest is persistent enhancement of the radar backscatter power during HF on at several HF frequencies. The persistent enhancement is induced with the HF frequency slightly lower than foF2 by a few hundred kHz; by contrast the persistent enhancement does not appear when the HF frequency is equal to and higher than foF2 or lower than foF2 by more than 500 kHz. When persistent enhancements of the radar backscatter power appear, two case studies show that the local plasma frequency at the reflection height of the O-mode polarization wave is close to the second or third electron gyroharmonic frequencies, but one case study shows that the local plasma frequency at the reflection height is significantly different from the third electron gyroharmonic frequency

Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP) facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.<p><b>Keywords.</b> Active experiments – Auroral ionosphere – Wave-particle interaction

Cancer sporadique du rein chez l'adulte jeune de moins de 45 ans

Notre étude a concerné, entre 1985 et 2003, 64 patients traités à la clinique urologique du CHU de Nantes âgés de moins de 45 ans et atteints d'un cancer du rein. En dépit des apports de l'imagerie, un mode de découverte symptomatique en rapport avec un retard diagnostic a été retrouvé dans 62% des cas. Ce mode de découverte a été lié à des critères pronostics péjoratifs pour le stade tumoral et le grade nucléaire. La survie globale à 10 ans a été de 70,9%, la survie spécifique à 10 ans a été de 74,8% et la survie sans récidive a été de 70% à 10ans. Les facteurs pronostics majeurs ont été le stade tumoral, le grade nucléaire, le score ASA. Dans une moindre mesure, le grade nucléaire et le mode de découverte ont été des facteurs pronostic en analyse univariée.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Novel artificial optical annular structures in the high latitude ionosphere over EISCAT

The EISCAT low-gain HF facility has been used repeatedly to produce artificially stimulated optical emissions in the F-layer ionosphere over northern Scandinavia. On 12 November 2001, the high-gain HF facility was used for the first time. The pump beam zenith angle was moved in 3° steps along the north-south meridian from 3°N to 15°S, with one pump cycle per position. Only when pumping in the 9°S position were annular optical structures produced quite unexpectedly. The annuli were approximately centred on the pump beam but outside the −3 dB locus. The optical signature appears to form a cylinder, which was magnetic field-aligned, rising above the pump wave reflection altitude. The annulus always collapsed into the well-known optical blobs after ∼60 s, whilst descending many km in altitude. All other pump beam directions produced optical blobs only. The EISCAT UHF radar, which was scanning from 3° to 15°S zenith angle, shows that enhanced ion-line backscatter persisted throughout the pump on period and followed the morphology of the optical signature. These observations provide the first experimental evidence that Langmuir turbulence can accelerate electrons sufficiently to produce the optical emissions at high latitudes. Why the optical annulus forms, and for only one zenith angle, remains unexplained