Observations of the missing baryons in the warm-hot intergalactic medium.

It has been known for decades that the observed number of baryons in the local Universe falls about 30-40 per cent short1,2 of the total number of baryons predicted 3 by Big Bang nucleosynthesis, as inferred4,5 from density fluctuations of the cosmic microwave background and seen during the first 2-3 billion years of the Universe in the so-called 'Lyman α forest'6,7 (a dense series of intervening H I Lyman α absorption lines in the optical spectra of background quasars). A theoretical solution to this paradox locates the missing baryons in the hot and tenuous filamentary gas between galaxies, known as the warm-hot intergalactic medium. However, it is difficult to detect them there because the largest by far constituent of this gas-hydrogen-is mostly ionized and therefore almost invisible in far-ultraviolet spectra with typical signal-to-noise ratios8,9. Indeed, despite large observational efforts, only a few marginal claims of detection have been made so far2,10. Here we report observations of two absorbers of highly ionized oxygen (O VII) in the high-signal-to-noise-ratio X-ray spectrum of a quasar at a redshift higher than 0.4. These absorbers show no variability over a two-year timescale and have no associated cold absorption, making the assumption that they originate from the quasar's intrinsic outflow or the host galaxy's interstellar medium implausible. The O VII systems lie in regions characterized by large (four times larger than average 11 ) galaxy overdensities and their number (down to the sensitivity threshold of our data) agrees well with numerical simulation predictions for the long-sought warm-hot intergalactic medium. We conclude that the missing baryons have been found.

Impaired bone remodeling in children with osteogenesis imperfecta treated and untreated with bisphosphonates: the role of DKK1, RANKL, and TNF-α.

UNLABELLED: In this study, we investigated the bone cell activity in patients with osteogenesis imperfecta (OI) treated and untreated with neridronate. We demonstrated the key role of Dickkopf-1 (DKK1), receptor activator of nuclear factor-κB ligand (RANKL), and tumor necrosis factor alpha (TNF-α) in regulating bone cell of untreated and treated OI subjects. These cytokines could represent new pharmacological targets for OI. INTRODUCTION: Bisphosphonates are widely used in the treatment of children with osteogenesis imperfecta (OI) with the objective of reducing the risk of fractures. Although bisphosphonates increase bone mineral density in OI subjects, the effects on fracture incidence are conflicting. The aim of this study was to investigate the mechanisms underlying bone cell activity in subjects with mild untreated forms of OI and in a group of subjects with severe OI treated with cycles of intravenous neridronate. METHODS: Sclerostin, DKK1, TNF-α, RANKL, osteoprotegerin (OPG), and bone turnover markers were quantified in serum of 18 OI patients (12 females, mean age 8.86 ± 3.90), 8 of which were receiving cyclic intravenous neridronate, and 21 sex- and age-matched controls. The effects on osteoblastogenesis and OPG expression of media conditioned by the serum of OI patients and anti-DKK1 neutralizing antibody were evaluated. Osteoclastogenesis was assessed in cultures from patients and controls. RESULTS: DKK1 and RANKL levels were significantly increased both in untreated and in treated OI subjects with respect to controls. The serum from patients with high DKK1 levels inhibited both osteoblast differentiation and OPG expression in vitro. High RANKL and low OPG messenger RNA (mRNA) levels were found in lymphomonocytes from patients. High amounts of TNF-α were expressed by monocytes, and an elevated percentage of circulating CD11b-CD51/CD61+ osteoclast precursors was observed in patients. CONCLUSIONS: Our study demonstrated the key role of DKK1, RANKL, and TNF-α in regulating bone cell activity of subjects with OI untreated and treated with bisphosphonates. These cytokines could represent new pharmacological targets for OI patients.

An improved procedure for identifying fiber types in ovine muscles.

An improved histochemical procedure has been developed for the identification of three muscle fiber types (ßR, αR, αW) in two ovine muscles. This procedure can be used in lieu of the traditional reciprocal procedures of using an oxidative enzyme and ATPase to identify fiber types. The advantage of this simultaneous staining procedure is that it eliminates duplication of effort and time plus it distinguishes the αR (intermediate) fibers more clearly than the traditional methods. For best results, muscle samples must be evaluated within 2h of slaughtering the animal and care must be taken to monitor the pH at regular intervals. More research is needed to determine specific conditions, i.e. sample time, pH, enzyme activity, etc., before this method can be recommended as the most appropriate procedure for determining fiber type in muscles of other species.

Broad Emission Line Regions in Active Galactic Nuclei: The Link with the Accretion Power.

We present a model that relates the width of the broad emission lines of active galactic nuclei (AGNs) to the Keplerian velocity of an accretion disk at a critical distance from the central black hole. This critical distance falls in a region bounded on the inward side by the transition radius between the radiation pressure- and the gas pressure-dominated region of the accretion disk and on the outward side by the maximum radius below which a stabilizing, radially accreting and vertically outflowing corona exists. We show that in the framework of this picture, the observed range of Hbeta FWHMs from broad-line to narrow-line type 1 AGNs is well reproduced as a function of the accretion rate. This interval of velocities is the only permitted range and goes from approximately 20,000 km s-1 for sub-Eddington accretion rates to approximately 1000 km s-1 for Eddington accretion rates.

Quality of Dry-Cured Hams Produced from Pre-Frozen Hams as Affected by Mechanical Tenderization and Vacuum Packaging 1.

Fifty frozen hams were thawed for 3 d at 2-3°C, skinned and partially defatted. Half the hams were passed twice through a Ross Industries needle tenderizer and half were not tenderized. All hams were dry-cured for 16 d with a mixture of salt, sugar, sodium nitrate and sodium nitrite. Cores of 2.54-cm diameter were obtained from the cushion of 5 hams from each group weekly for 5 weeks. Outer, middle and inner portions of the cores were analyzed for salt and nitrite. After curing, all hams were held at 13°C for 14 or 15 d for salt equalization. The intact hams were smoked and aged at 24°C until a yield of 82% or less was achieved. Half the hams in each group were then placed in vacuum bags and half were left uncovered. All were aged 4 additional weeks at 24°C. Hams were cut and examined visually, by a palatability panel, by shearing and by analyzing a center slice for moisture, salt and nitrite. Tenderization allowed faster salt and nitrite absorption but resulted in slightly lower flavor and overall satisfaction scores. Tenderized hams achieved the required 18% weight loss (82%) approximately 10 d sonner than non-tenderized hams. Vacuum packaged hams had higher final yields and contained a higher level of moisture and lower level of salt than non-vacuum packaged hams. Shear values in semitendinosus muscles were greater for tenderized than for nontenderized hams while shear values in biceps femoris muscles were higher in non-vacuum packaged than in the vacuum packaged hams. Aerobic and yeast and mold counts were higher while lactobacillus counts were lower in non-tenderized than in tenderized hams. Aerobic and lactobacillus counts were higher in vacuum packaged than in non-vacuum packaged hams. In general, tenderization allowed faster curing and aging while final aging in vacuum bags allowed higher yields.