Treatment response in relation to inflammatory and axonal surrogate marker in multiple sclerosis

BACKGROUND: This study aimed to investigate if treatment response could retrospectively be related to inflammatory or axonal pathology as measured by plasma surrogate markers. METHODS: In this 1-year observational study 30 multiple sclerosis (MS) patients with relapsing-remitting disease were treated with intramuscular IFNbeta-1a or subcutaneous IFNbeta-1b. Responders and nonresponders were defined according to clinical and magnetic resonance imaging criteria. The control group consisted of 14 healthy subjects. Plasma levels of surrogate markers for inflammation (nitric oxide metabolites (NOx)), astrocytic activation (S100B) and axonal damage (NfH(SM135)) were measured using standard assays. RESULTS: There were 11 nonresponders and 19 responders to IFNbeta treatment. Median S100B levels were elevated in a higher proportion of treatment responders (63%, 42.9 pg/mL) compared to nonresponders (18%, 11.7 pg/mL, P < 0.05, Fisher's exact test) and controls (0%, 2 pg/mL, P < 0.001). Levels of NOx were found to be more frequently elevated in nonresponders (72%, 39 microM) compared to healthy controls (0%, 37 microM, P < 0.05). Levels of NfH(SM135) were more frequently elevated in responders (58%, 300 pg/mL, P < 0.001) and nonresponders (72%, 500 pg/mL, P < 0.001) compared to controls (0%, 4.5 pg/mL). CONCLUSION: Patients with relapsing-remitting MS who had surrogate marker supported evidence for astrocytic activation responded more frequently to treatment with IFNbeta

The effect of collisional enhancement of Balmer lines on the determination of the primordial helium abundance

This paper describes a new determination of the primordial helium abundance (Y_P), based on the abundance analysis of five metal-poor extragalactic HII regions. For three regions of the sample (SBS 0335-052, I Zw 18, and H29) we present tailored photoionization models based on improved calculations with respect to previous models. In particular, we use the photoionization models to study quantitatively the effect of collisional excitation of Balmer lines on the determination of the helium abundance (Y) in the individual regions. This effect is twofold: first, the intensities of the Balmer lines are enhanced with respect to the pure recombination value, mimicking a higher hydrogen abundance; second, the observed reddening is larger than the true extinction, due to the differential effect of collisions on different Balmer lines. In addition to these effects, our analysis takes into account the following features of HII regions: (i) the temperature structure, (ii) the density structure, (iii) the presence of neutral helium, (iv) the collisional excitation of the HeI lines, (v) the underlying absorption of the HeI lines, and (vi) the optical thickness of the HeI lines. The object that shows the highest increase in Y after the inclusion of collisional effects in the analysis is SBS 0335-052, whose helium abundance has been revised by Delta Y = +0.0107. The revised Y values for the five objects in our sample yield an increase of +0.0035 in Y_P, giving Y_P = 0.2391 +/- 0.0020.Comment: 59 pages, 8 figures. AAS Latex. Accepted for publication in the Astrophysical Journa

Neutral gas in Lyman-alpha emitting galaxies Haro 11 and ESO 338-IG04 measured through sodium absorption

Context. The Lyman alpha emission line of galaxies is an important tool for finding galaxies at high redshift, and thus probe the structure of the early universe. However, the resonance nature of the line and its sensitivity to dust and neutral gas is still not fully understood. Aims. We present measurements of the velocity, covering fraction and optical depth of neutral gas in front of two well known local blue compact galaxies that show Lyman alpha in emission: ESO 338-IG 04 and Haro 11. We thus test observationally the hypothesis that Lyman alpha can escape through neutral gas by being Doppler shifted out of resonance. Methods. We present integral field spectroscopy from the GIRAFFE/Argus spectrograph at VLT/FLAMES in Paranal, Chile. The excellent wavelength resolution allows us to accurately measure the velocity of the ionized and neutral gas through the H-alpha emission and Na D absorption, which traces the ionized medium and cold interstellar gas, respectively. We also present independent measurements with the VLT/X-shooter spectrograph which confirm our results. Results. For ESO 338-IG04, we measure no significant shift of neutral gas. The best fit velocity is -15 (16) km/s. For Haro 11, we see an outflow from knot B at 44 (13) km/s and infalling gas towards knot C with 32 (12) km/s. Based on the relative strength of the Na D absorption lines, we estimate low covering fractions of neutral gas (down to 10%) in all three cases. Conclusions. The Na D absorption likely occurs in dense clumps with higher column densities than where the bulk of the Ly-alpha scattering takes place. Still, we find no strong correlation between outflowing neutral gas and a high Lyman alpha escape fraction. The Lyman alpha photons from these two galaxies are therefore likely escaping due to a low column density and/or covering fraction.Comment: 9 pages, 3 figure

The Hydrodynamics of the Gulf of Cadiz and the Exchange of Water Masses Through the Gibraltar Strait

Studies on the exchange of water masses through the Gibraltar Strait, between the Atlantic Ocean and the Mediterranean Sea, are numerous, mainly in recent years. However, there is a lack of works of synthesis about the mechanism, distribution and nature of the water masses etc., based on more recent data. On the other hand, the establishment of temperature and salinity data for the waters partially covering the continental shelf near Câdiz, has demonstrated the presence, in this area, of North Atlantic Surface Water (NASW), to about 140 metres depth, with clear seasonal variations. At a deeper level, some North Atlantic Central Water (NACW) has been detected, but the presence of Mediterranean Water (MW), which circulates below 500 metres, in the continental slope, has not been observed

Nuevos datos sobre las helmintofaunas parasíticas de micromamíferos en las islas Pitiusas. I.

Abstract not availabl

Gas-dynamic shock heating of post-flare loops due to retraction following localized, impulsive reconnection

We present a novel model in which shortening of a magnetic flux tube following localized, three-dimensional reconnection generates strong gas-dynamic shocks around its apex. The shortening releases magnetic energy by progressing away from the reconnection site at the Alfven speed. This launches inward flows along the field lines whose collision creates a pair of gas-dynamic shocks. The shocks raise both the mass density and temperature inside the newly shortened flux tube. Reconnecting field lines whose initial directions differ by more that 100 degrees can produce a concentrated knot of plasma hotter that 20 MK, consistent with observations. In spite of these high temperatures, the shocks convert less than 10% of the liberated magnetic energy into heat - the rest remains as kinetic energy of bulk motion. These gas-dynamic shocks arise only when the reconnection is impulsive and localized in all three dimensions; they are distinct from the slow magnetosonic shocks of the Petschek steady-state reconnection model

Multiwavelength analysis of the Lyman alpha emitting galaxy Haro 2: relation between the diffuse Lyman alpha and soft X-ray emissions

In order to use Lyman alpha (Lya) emission as star formation tracer in cosmological studies, we must understand how the resonant scattering affects the escape fraction of the Lya photons. Thus, high spatial resolution multiwavelength studies of nearby Lya emitters, like Haro 2, are highly needed. For that purpose, we have used Chandra X-ray and HST (UV, optical and NIR) images of Haro 2, and STIS and ground-based spectral images along its major and minor axes, to characterize the Lya emission and the properties of the stellar population. The UV, Ha (Halpha) and FIR luminosities of the Haro 2 nuclear starburst are reproduced using evolutionary synthesis models assuming a young stellar population with ages ~3.5-5.0 Myr, affected by differential interstellar extinctions. The observed X-ray emission is attributed to gas heated by the mechanical energy released by the starburst (soft component) and a Ultra-Luminous X-ray source candidate (hard). Both compact and diffuse Lya components are observed. Whereas Lya is spatially decoupled from Balmer lines emission, Balmer decrement and UV continuum, the diffuse Lya component is spatially correlated with the diffuse soft X-ray emission. Moreover, unlike the compact one, diffuse Lya shows luminosities larger than predicted from Ha, assuming case B recombination and dust extinction as derived from Ha/Hbeta. We propose that, whereas the compact Lya emission is associated to the massive stellar clusters and is affected by outflows and dust extinction, the diffuse Lya originates in gas ionized by the hot plasma responsible for the soft X-ray radiation, as suggested by their spatial correlation and by the measured L(Ha)/LsoftX ratios. Calibration of Lya as star formation rate tracer should therefore include both effects (destruction vs. enhancement) to avoid biases in the study of galaxies at cosmological distances.Comment: Accepted for publication in A&A, 18 pages, 8 figures, 9 tables. If problems with quality of images, see http://www.cab.inta-csic.es/users/otih/haro2-v63.clean.pd

Physical properties and evolutionary state of the Lyman alpha emitting starburst galaxy IRAS 08339+6517

Though Lyman alpha emission (Lya) is one of the most used tracers of massive star formation at high redshift, a correct understanding of radiation transfer effects by neutral gas is required to properly quantify the star formation rate along the history of the Universe. We are embarked in a program to study the properties of the Lya emission (spectral profile, spatial distribution, relation to Balmer lines intensity,...) in several local starburst galaxies. We present here the results obtained for IRAS 08339+6517. Using evolutionary population synthesis models, we have characterized the properties of the starburst (UV continuum, Halpha, total infrared and X-ray emissions, etc.), which transformed 1.4e+8 Mo of gas into stars around 5-6 Myr ago. In addition to the central compact emission blob, we have identified a diffuse Lya emission component smoothly distributed over the whole central area of IRAS 08339+6517. This diffuse emission is spatially decoupled from the UV continuum, the Halpha emission or the Halpha/Hbeta ratio. Both locally and globally, the Lya/Halpha ratio is lower than the Case B predictions, even after reddening correction, with an overall Lya escape fraction of only 4%. We conclude that in IRAS 08339+6517 the resonant scattering of Lya photons by an outflowing shell of neutral gas causes their highly-efficient destruction by dust, which explains the low Lya escape fraction measured. These results stress again the importance of a proper correction of scattering and transfer effects when using Lya to derive the star formation rate in high-redshift galaxies.Comment: Accepted for publication in A&A, 17 pages, 13 figures, 8 tables. If problems with quality of images, see https://cloud.cab.inta-csic.es/public.php?service=files&file=%2Fotih%2Ffiles%2Foti_mas%2Firas%2Firas-v53.ack_referee.pd