An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre.

Evidence has mounted in recent decades that outflows of matter and energy from the central few parsecs of our Galaxy have shaped the observed structure of the Milky Way on a variety of larger scales1. On scales of 15 parsecs, the Galactic Centre has bipolar lobes that can be seen in both the X-ray and radio parts of the spectrum2,3, indicating broadly collimated outflows from the centre, directed perpendicular to the Galactic plane. On larger scales, approaching the size of the Galaxy itself, γ-ray observations have revealed the so-called 'Fermi bubble' features4, implying that our Galactic Centre has had a period of active energy release leading to the production of relativistic particles that now populate huge cavities on both sides of the Galactic plane. The X-ray maps from the ROSAT all-sky survey show that the edges of these cavities close to the Galactic plane are bright in X-rays4-6. At intermediate scales (about 150 parsecs), radio astronomers have observed the Galactic Centre lobe, an apparent bubble of emission seen only at positive Galactic latitudes7,8, but again indicative of energy injection from near the Galactic Centre. Here we report prominent X-ray structures on these intermediate scales (hundreds of parsecs) above and below the plane, which appear to connect the Galactic Centre region to the Fermi bubbles. We propose that these structures, which we term the Galactic Centre 'chimneys', constitute exhaust channels through which energy and mass, injected by a quasi-continuous train of episodic events at the Galactic Centre, are transported from the central few parsecs to the base of the Fermi bubbles4.

Impaired control of weight bearing ankle inversion in subjects with chronic ankle instability.

BACKGROUND: Previous studies have proposed that evertor muscle weakness represents an important factor affecting chronic ankle instability. For research purposes, ankle evertor strength is assessed by means of isokinetic evaluations. However, this methodology is constraining for daily clinical use. The present study proposes to assess ankle evertor muscle weakness using a new procedure, one that is easily accessible for rehabilitation specialists. To do so, we compared weight bearing ankle inversion control between patients suffering from chronic ankle instability and healthy subjects. METHODS: 12 healthy subjects and 11 patients suffering from chronic ankle instability conducted repetitions of one leg weight bearing ankle inversion on a specific ankle destabilization device equipped with a gyroscope. Ankle inversion control was performed by means of an eccentric recruitment of evertor muscles. Instructions were to perform, as slow as possible, the ankle inversion while resisting against full body weight applied on the tested ankle. RESULTS: Data clearly showed higher angular inversion velocity peaks in patients suffering from chronic ankle instability. This illustrates an impaired control of weight bearing ankle inversion and, by extension, an eccentric weakness of evertor muscles. INTERPRETATION: The present study supports the hypothesis of a link between the decrease of ankle joint stability and evertor muscle weakness. Moreover, it appears that the new parameter is of use in a clinical setting.

Peroneal reaction time measurement in unipodal stance for two different destabilization axes.

BACKGROUND: The variability of peroneal reaction time measurements is a major problem when using this parameter to control rehabilitation or proprioceptive training processes. In order to control peroneal reaction time values, some extrinsic factors should be considered. The purpose of this study was to measure peroneal reaction time in unipodal stance for two different destabilization axes. METHODS: The peroneal reaction time of 10 healthy subjects was measured from kinematic and electromyograhic data in an experimental study using an ankle destabilization device. FINDINGS: In a preliminary analysis, results showed that the destabilization axis orientation did not affect peroneal reaction time values (68.5 ms, standard deviation=9.5 ms and 71.5 ms, standard deviation=8 ms for destabilizations in the frontal plane and around the Henke's axis, respectively). However, the inter-trial variance of inversion velocity peaks explained between 40% and 49% of the peroneal reaction time variance. When trials were selected on the basis of homogeneous inversion velocity peaks, results showed that peroneal reaction time values for the peroneus brevis were shorter during inversion movements performed around the physiological Henke's tilting axis (63 ms, standard deviation=9 ms vs. 71 ms, standard deviation=8 ms). INTERPRETATION: Our findings evidenced that tilting axis orientation must be considered as an extrinsic factor that may influence peroneal reaction time. Moreover it also seems necessary to consider inversion speed values to adequately compare peroneal reaction time values.

Compact sources as the origin of the soft gamma-ray emission of the Milky Way.

The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.

Quantitation of homocysteine in human plasma by capillary electrophoresis and laser-induced fluorescence detection.

Homocysteine (Hcy) represents a branching point between the transsulfuration and transmethylation pathway of methionine. A large increase of plasma concentration of Hcy is observed in patients with inherited hyperhomocysteinemia. A moderated increase (above 10 microM) is also observed in various pathological conditions, such as arterial occlusion, hypertension, hyperlipidemia and chronic renal failure. While amino acids were largely studied using capillary electrophoresis with UV or laser-induced fluorescence detection (LIF), thiol-amino acids were not. In this work we present a new approach for testing homocysteine in human plasma using CE-LIF and fluorescein isothiocyanate. The low fluorescence yield of the fluorescein thiocarbamyl (FTC) thiol-amino acids limits, probably, the sensitivity of the detection to 8 x 10(-10) M (instead of 10(-12) M for FTC-arginine).