A test of the nature of cosmic acceleration using galaxy redshift distortions.

Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the equations of cosmic expansion, accounting for about 75 per cent of the total energy density in the Universe. The simplest option for this 'dark energy' corresponds to a 'cosmological constant', perhaps related to the quantum vacuum energy. Physically viable alternatives invoke either the presence of a scalar field with an evolving equation of state, or extensions of general relativity involving higher-order curvature terms or extra dimensions. Although they produce similar expansion rates, different models predict measurable differences in the growth rate of large-scale structure with cosmic time. A fingerprint of this growth is provided by coherent galaxy motions, which introduce a radial anisotropy in the clustering pattern reconstructed by galaxy redshift surveys. Here we report a measurement of this effect at a redshift of 0.8. Using a new survey of more than 10,000 faint galaxies, we measure the anisotropy parameter beta = 0.70 +/- 0.26, which corresponds to a growth rate of structure at that time of f = 0.91 +/- 0.36. This is consistent with the standard cosmological-constant model with low matter density and flat geometry, although the error bars are still too large to distinguish among alternative origins for the accelerated expansion. The correct origin could be determined with a further factor-of-ten increase in the sampled volume at similar redshift.

A large population of galaxies 9 to 12 billion years back in the history of the Universe.

To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs. Galaxies in the young Universe have hitherto mainly been identified using their expected optical colours, but this leaves open the possibility that a significant population remains undetected because their colours are the result of a complex mix of stars, gas, dust or active galactic nuclei. Here we report the results of a flux-limited I-band survey of galaxies at look-back times of 9 to 12 billion years. We find 970 galaxies with spectroscopic redshifts between 1.4 and 5. This population is 1.6 to 6.2 times larger than previous estimates, with the difference increasing towards brighter magnitudes. Strong ultraviolet continua (in the rest frame of the galaxies) indicate vigorous star formation rates of more than 10-100 solar masses per year. As a consequence, the cosmic star formation rate representing the volume-averaged production of stars is higher than previously measured at redshifts of 3 to 4.

Bioluminescent flow sensor for L-phenylalanine determination in serum.

A highly sensitive and rapid bioluminescent flow sensor was developed for the determination of the content of L-phenylalanine (Phe) in serum by monitoring the reduced form of nicotinamide adenine dinucleotide (NADH), produced by immobilized phenylalanine dehydrogenase (PheDH), with bacterial bioluminescent enzymes immobilized on a separate nylon coil. The L-PheDHs extracted from Bacillus badius, Bacillus sphaericus and Rhodococcus sp. M 4 were investigated and the performances of the three immobilized L-PheDH's were analysed. The B. badius reactor was found to give higher transformation rate and better sensitivity; the response was linear from 1 to 100 microM at 25 degrees , with a detection limit of 10 pmoles (0.5 microM). The intra- and inter-assay coefficients of variation were less than 5% and recoveries ranged from 90 to 101%. The results agreed well with those obtained with a chromatographic method for the Phe determination in serum and with the normal reference values.

Neonatal screening for cystic fibrosis by dried blood spot trypsin assay. Results in 47 127 newborn infants from a homogeneous population.

47 127 newborn infants from the Emilia-Romagna region were screened for cystic fibrosis by dried blood spot trypsin assay. In the initial 12 099 subjects screened with a non-standardized method, two children with cystic fibrosis were observed. Of the remaining 35 028 newborn infants, 299 showed high immunoreactive trypsin values; retesting revealed persistent elevation in 11. Sweat testing confirmed cystic fibrosis in 6 subjects and was normal in 5. Clinical monitoring of these 5 children has, as yet, shown no pathological signs. No false-negative test results have yet been identified. In our region, cystic fibrosis frequency would appear to be 1 case every 5 890 newborn infants. Our study confirms that elevated immunoreactive trypsin is characteristic of newborn infants with cystic fibrosis and that screening by determination of immunoreactive trypsin is of great benefit since it allows early diagnosis and a rational approach to therapy.

[Neonatal screening for congenital hypothyroidism. Experience at a Regional Center]. / Lo screening neonatale dell'ipotiroidismo congenito. Esperienza di un centro regionale.

We examined 107,670 infants born in the Italian region Emilia-Romagna. Capillary blood samples for contemporary T4 and TSH radioimmunoassay were collected on the 3rd, 4th, 5th, 6th, 7th or between the 7th and the 15th day of life on filter paper. In our method the threshold value for recall for a second assay was calculated taking into account the mean - 2 SD of each session for T4, and fixing between 30 and 50 microU/ml the threshold value for TSH. The re-call percentage was 0.74%. 21 subjects confirmed to be affected by congenital hypothyroidism; this corresponds to a frequency in our region of 1 case every 5,127 infants. 12 subjects had a TBG deficiency, this corresponds to a frequency of 1 case every 8,972 infants. No cases of secondary hypothyroidism were found up to date.