New determinations of gamma-ray line intensities of the Ep = 550 keV and Ep = 1747 keV resonances of the 13-C(p,gamma)14-N reaction

Gamma-ray angular distributions for the resonances at Ep = 550 keV and 1747 keV of the radiative capture reaction 13-C(p,g)14-N have been measured, using intense proton beams on isotopically pure 13-C targets. Relative intensities for the strongest transitions were extracted with an accuracy of typically five per cent, making these resonances new useful gamma-ray standards for efficiency calibration in the energy range Egamma = 1.6 to 9 MeV.Comment: 17 pages, 6 figures, Nuclear Instruments and Methods, Sec. A, accepte

Effects of spatial dispersion in near-field radiative heat transfer between two parallel metallic surfaces

We study the heat transfer between two parallel metallic semi-infinite media with a gap in the nanometer-scale range. We show that the near-field radiative heat flux saturates at distances smaller than the metal skin depth when using a local dielectric constant and investigate the origin of this effect. The effect of non-local corrections is analysed using the Lindhard-Mermin and Boltzmann-Mermin models. We find that local and non-local models yield the same heat fluxes for gaps larger than 2 nm. Finally, we explain the saturation observed in a recent experiment as a manifestation of the skin depth and show that heat is mainly dissipated by eddy currents in metallic bodies.Comment: Version without figures (8 figures in the complete version

Primary Invasive Aspergillosis of the Digestive Tract: Report of Two Cases and Review of the Literature

Abstract : Background: : Disseminated aspergillosis is thought to occur as a result of vascular invasion from the lungs with subsequent bloodstream dissemination, and portals of entry other than sinuses and/or the respiratory tract remain speculative. Methods: : We report two cases of primary aspergillosis in the digestive tract and present a detailed review of eight of the 23 previously-published cases for which detailed data are available. Results and Conclusion: : These ten cases presented with symptoms suggestive of typhlitis, with further peritonitis requiring laparotomy and small bowel segmental resection. All cases were characterized by the absence of pulmonary disease at the time of histologically-confirmed gastrointestinal involvement with vascular invasion by branched Aspergillus hyphae. These cases suggest that the digestive tract may represent a portal of entry for Aspergillus species in immunocompromised patient

Efficacité énergétique et émissions de GES de systèmes d'élevage bovin viande en Amazonie.

L?élevage au Brésil, 1er exportateur mondial de viande, serait responsable de plus de 75% des déforestations et 19% des émissions nationales de gaz à effet de serre (GES). L?objectif de notre étude est de mettre au point une première méthode de calcul d?efficacité énergétique et d?émissions de GES des systèmes d?élevage amazoniens, en se basant sur la méthode Planète. Une révision de l?ensemble des coefficients énergétiques et des facteurs d?émission de GES ainsi que l?ajout de certaines rubriques ont permis d?élaborer un logiciel de calcul adapté au contexte régional. Six systèmes d?élevage bovin allaitants ont été étudiés lors d?enquêtes directes : un naisseur, trois engraisseurs et deux naisseurs-engraisseurs avec des troupeaux compris entre 650 et 3700 têtes, des charges instantanées variables, liées à des gestions de pâturage et des pratiques alimentaires très diversifiées. Les consommations d?énergie sont en moyenne de 9 724 MJ/t poids vif/an (min=4 019 MJ/t, max=15 243 MJ/t). Les principaux postes, responsables de 56% à 93% des consommations d?énergie, sont les achats d?aliments, la fertilisation des pâturages et l?achat de carburant (et d?animaux pour les engraisseurs). Ces systèmes d?élevage basés sur des ressources herbagères abondantes, utilisant peu d?intrants et d?infrastructures sont peu consommateurs d?énergie, comparés aux autres systèmes dans le monde. Les différences d?efficacité énergétique sont liées à l?efficacité productive végétale et animale et non au degré d?intensité d?utilisation des intrants. Les émissions de GES sont importantes, en moyenne de 19,8 t eq CO2/ t poids vif/ an (min= 11,2 t eq CO2/t, max= 40,5 t eq CO2/t). La déforestation avec un amortissement linéaire sur 20 ans représente de zéro jusqu?à 75% des émissions totales. Nous avons aussi montré l?intérêt environnemental de systèmes productifs intégrant agriculture et élevage. Ces résultats à l?échelle des exploitations participent de la prise de conscience individuelle des éleveurs et renforcent les engagements locaux pour la « déforestation zéro ». La comparaison avec d?autres systèmes d?élevage dans le monde souligne l?intérêt d?une production animale maitrisée, en matière de déforestation et d?intensification, sous les tropiques humides. Plus largement cette étude montre la validité de cette méthode et devrait permettre de généraliser ces bilans

Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo₂ cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs

Multiple relativistic outbursts of GRS 1915+105: radio emission and internal shocks

We present 5-GHz MERLIN radio images of the microquasar GRS 1915+105 during two separate outbursts in 2001 March and 2001 July, following the evolution of the jet components as they move outwards from the core of the system. Proper motions constrain the intrinsic jet speed to be >0.57c, but the uncertainty in the source distance prevents an accurate determination of the jet speed. No deceleration is observed in the jet components out to an angular separation of about 300mas. Linear polarisation is observed in the approaching jet component, with a gradual rotation in position angle and a decreasing fractional polarisation with time. Our data lend support to the internal shock model whereby the jet velocity increases leading to internal shocks in the pre-existing outflow before the jet switches off. The compact nuclear jet is seen to re-establish itself within two days, and is visible as core emission at all epochs. The energetics of the source are calculated for the possible range of distances; a minimum power of 1-10 per cent of the Eddington luminosity is required to launch the jet.Comment: 18 pages, 14 figures, accepted for publication in MNRAS. For higher-resolution versions of Figures 3, 5, and 12, see http://remote.science.uva.nl/~jmiller/grs1915/figures.htm

Characterizing a new class of variability in GRS 1915+105 with simultaneous INTEGRAL/RXTE observations

We report on the analysis of 100 ks INTEGRAL observations of the Galactic microquasar GRS 1915+105. We focus on INTEGRAL Revolution number 48 when the source was found to exhibit a new type of variability as preliminarily reported in Hannikainen et al. (2003). The variability pattern, which we name $\xi$, is characterized by a pulsing behaviour, consisting of a main pulse and a shorter, softer, and smaller amplitude precursor pulse, on a timescale of 5 minutes in the JEM-X 3-35 keV lightcurve. We also present simultaneous RXTE data. From a study of the individual RXTE/PCA pulse profiles we find that the rising phase is shorter and harder than the declining phase, which is opposite to what has been observed in other otherwise similar variability classes in this source. The position in the colour-colour diagram throughout the revolution corresponds to State A (Belloni et al. 2000) but not to any previously known variability class. We separated the INTEGRAL data into two subsets covering the maxima and minima of the pulses and fitted the resulting two broadband spectra with a hybrid thermal--non-thermal Comptonization model. The fits show the source to be in a soft state characterized by a strong disc component below ~6 keV and Comptonization by both thermal and non-thermal electrons at higher energies.Comment: Accepted for publication in A&A. 11 pages, 10 figures, 4 in colour. Original figures can be found at http://www.astro.helsinki.fi/~diana/grs1915_rev48. Author affiliations correcte

Geotechnologies for monitoring pasture degradation levels in Brazil.

Extensive livestock represents around 93% of cattle production in Brazil and pasture is its main food source. For this reason, the sector considers pasture degradation an important problem, being responsible for economic and environmental losses. Several sources indicate that more than 60% of the 160 million hectare of Brazilian pastures shows some level of degradation. The need for precise information about degraded pasture levels, localization and quantities leaded to the GEODEGRADE project. More details and results can be found at the website: http://www.geodegrade.cnpm.embrapa.br