A 46
g BGO (Bi
4Ge
3O
12) scintillating bolometer has been tested at 20
mK as a prototype for dark matter direct detection in the frame of the ROSEBUD (Rare Objects SEarch with Bolometers ...UndergrounD) collaboration. The bolometer has been operated first in Orsay and then in an ultra-low background environment at the Canfranc Underground Laboratory. We analyze its response both in heat and light, and its particle discrimination capability. Light yield under γ-ray excitation at several energies (from 88.0 to 1633.3
keV) and the relative light output for different particles (β/γ, α and neutrons) have been estimated. The analysis focuses on the discrimination of nuclear recoils, like those produced by hypothetical weakly interacting massive particles (WIMPs), against electron recoils, produced by β/γ radioactive background.
We study the infrared (IR) properties of high-redshift galaxies using deep Spitzer 24, 70, and 160 mu m data. Our primary interest is to improve the constraints on the total IR luminosities, Lir, of ...these galaxies. We combine the Spitzer data in the southern Extended Chandra Deep Field with a K sub(s)-band-selected galaxy sample and photometric redshifts from the Multiwavelength Survey by Yale-Chile. We used a stacking analysis to measure the average 70 and 160 mu m flux densities of 1.5 < z < 2.5 galaxies as a function of 24 mu m flux density, X-ray activity, and rest-frame near-IR color. Galaxies with 1.5 < z < 2.5 and unk = 53-250 mu Jy have Lir derived from their average 24-160 mu m flux densities within factors of 2-3 of those inferred from the 24 mu m flux densities only. However, Lir derived from the average 24-160 mu m flux densities for galaxies with S sub(24) > 250 mu Jy and 1.5 < z < 2.5 are lower than those Inferred using only the 24 mu m flux density by factors of 2-10. Galaxies with S sub(24) > 250 mu Jy have S sub(70)/S sub(24) flux ratios comparable to sources with X-ray detections or red rest-frame IR colors, suggesting that warm dust possibly heated by AGNs may contribute to the high 24 mu m emission. Based on the average 24-160 mu um flux densities, nearly all 24 mu m-selected galaxies at 1.5 < z < 2.5 have Lir < 6 x 10 super(12) L unk, which, if attributed to star formation, corresponds to unk < 1000 M unk yr super(-1). This suggests that high-redshift galaxies may have star formation efficiencies and feedback processes similar to those of local analogs. Objects with Lir > 6 x 10 super(12) L unk are quite rare, with a surface density similar to 30 plus or minus 10 deg super(-2), corresponding to similar to 2 plus or minus 1 x 10 super(-6) Mpc super(-3) over 1.5 < z < 2.5.
One hundred and five 15 μm-selected objects in three ISO ($\it Infrared~Space~Observatory$) deep survey fields (CFRS 3h, UDSR and UDSF) are studied on the basis of their high-quality optical spectra ...with resolution $R>1000$ from VLT/FORS2. ~92 objects (88%) have secure redshifts, ranging from 0 to 1.16 with a median value of $z_{\rm med}=0.587$. Considerable care is taken in estimating the extinction properties of individual galaxy, which can seriously affect diagnostic diagrams and estimates of star formation rates (SFRs) and of metal abundances. Two independent estimates of the extinction have been made, e.g. Balmer line ratio and energy balance between infrared (IR) and Hβ luminosities. For most of the sources, we find a good agreement between the two extinction coefficients (within ±0.64 rms in AV, the extinction in V band), with median values of AV(IR$) = 2.36$ and AV(Balmer$)= 1.82$ for $z>0.4$ luminous IR galaxies (LIRGs). At $z >0.4$, our sample show many properties (IR luminosity, continuum color, ionization and extinction) strikingly in common with those of local (IRAS) LIRGs studied by Veilleux et al. (CITE). Thus, our sample can provide a good representation of LIRGs in the distant Universe. We confirm that most (>77%) ISO 15 μm-selected galaxies are dominated by star formation. Oxygen abundances in interstellar medium in the galaxies are estimated from the extinction-corrected “strong” emission line ratios (e.g. $\ion{O}{ii}$/Hβ, $\ion{O}{iii}$/Hβ and $\ion{O}{iii}$/$\ion{O}{ii}$). The derived 12+log(O/H) values range from 8.36 to 8.93 for the $z>0.4$ galaxies with a median value of 8.67. Distant LIRGs present a metal content less than half of that of the local bright disks (i.e. L*). Their properties can be reproduced with infall models although one has to limit the infall time to avoid overproduction of metals at late times. The models predict that total masses (gas + stars) of the distant LIRGs are from $10^{11}~M_{\odot}$ to ≤$10^{12}~M_{\odot}$. A significant fraction of distant large disks are indeed LIRGs. Such massive disks could have formed ~50% of their metals and stellar masses since $z\sim1$.
Commercial low molecular mass heparin accelerates the inhibition of neutrophil elastase by mucus proteinase inhibitor, the predominant antielastase of lung secretions (Faller, B., Mély, Y., Gérard, ...D., and Bieth, J. G.(1992) Biochemistry 31, 8285-8290). To study the kinetic mechanism of this rate enhancement, we have isolated a 4.5-kDa heparin fragment from commercial heparin. This compound is fairly monodisperse as shown by analytical ultracentrifugation. It binds elastase and inhibitor with a 1:1 stoichiometry and an equilibrium dissociation constant of 3 and 210 nM, respectively. It also forms a tight complex with EI. Flow calorimetry shows that the inhibitor-heparin interaction is characterized by a large negative enthalpy change (ΔH0 = −45.2 kJ mol−1) and a small entropy change (ΔS = −23.7 J K−1 mol−1). Stopped-flow kinetics run under pseudo-first-order conditions (Io ⪢ Eo) show that in the absence of heparin the inhibition conforms to a simple bimolecular reaction, (Eq. 1)E+I⇌kdkaEI where, ka = 3.1 × 106 M−1s−1, kd= 10−4 s−1, and Ki= 33 pM, whereas in the presence of heparin, E and I react via a two-step mechanism, (Eq. 2)E+I⇌Ki∗EI∗⇌k−2k2EI where Ki∗ = 86 nM, k2 = 2.2 s−1, k−2 = 10−4 s−1, and Ki= 37 pM. Thus, heparin increases both the rate of inhibition by promoting the formation of a high affinity EI∗ intermediate and the rate of EI dissociation. Since the dissociation is negligible in bronchial secretions where the inhibitor concentration is much higher than Ki, it may be concluded that heparin significantly potentiates the inhibitor's antielastase potential in vivo.
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