Detection of Lyman-alpha Emitting Galaxies at Redshift z=4.55

Studies of the formation and early history of galaxies have been hampered by the difficulties inherent in detecting faint galaxy populations at high redshift. As a consequence, observations at the highest redshifts (3.5 < z < 5) have been restricted to objects that are intrinsically bright. These include quasars, radio galaxies, and some Ly alpha-emitting objects that are very close to (within ~10 kpc) -- and appear to be physically associated with -- quasars. But the extremely energetic processes which make these objects easy to detect also make them unrepresentative of normal (field) galaxies. Here we report the discovery using Keck spectroscopic observations of two Ly alpha-emitting galaxies at redshift z = 4.55, which are sufficiently far from the nearest quasar (~700 kpc) that radiation from the quasar is unlikely to provide the excitation source of the Ly alpha emission. Instead, these galaxies appear to be undergoing their first burst of star formation, at a time when the Universe was less than one billion years old.Comment: 8 pages, 1 landscape table, and 3 PostScript figures. Uses aaspp4.sty, flushrt.sty, aj_pt4.sty, overcite.sty (style macros available from xxx.lanl.gov) Figure 1 is bitmapped to 100 dpi. The original PostScript version of Fig. 1 is available via anonymous ftp to ftp://hubble.ifa.hawaii.edu/pub/preprints To appear in Natur

Current Density Functional approach to large quantum dots in intense magnetic fields

Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of the magnetic field (B) that can be attributed in a clear way to the formation of compressible and incompressible states of the system. The orbital and spin angular momenta, the total energy, ionization and electron chemical potentials of the ground state, as well as the frequencies of far-infrared edge modes are calculated as a function of B, and compared with available experimental and theoretical results.Comment: Typeset using Revtex, 17 pages and 13 Postscript figure

Do emotional difficulties and peer problems hew together from childhood to adolescence? The case of children with a history of developmental language disorder (DLD)

Children and adolescents with developmental language disorder (DLD) are, overall, vulnerable to difficulties in emotional adjustment and in peer relations. However, previous research has shown that different subgroups follow different trajectories in respect of quality of peer relations. Less is known of the trajectories of emotional development. We consider here the possibility that development in these two domains is interrelated: that is, the trajectories of emotional and peer problems will proceed in parallel. We conducted longitudinal joint trajectories analyses of emotional and peer relations in a sample of young people identified as having DLD at age 7 years and seen at intervals up to 16 years. Potential influences on joint trajectory group membership were examined. Findings revealed five distinct joint trajectories. Emotional and peer difficulties do hew together from childhood to adolescence for just over half of the sample, but not all. The variables most clearly associated with group membership were pragmatic language ability, prosociality and parental mental health. This is the first study to examine joint longitudinal trajectories of emotional and peer difficulties in individuals with DLD. We demonstrate that development in individuals with DLD is heterogeneous and identify three key variables associated with personal and social adjustment from childhood to adolescence. Theoretical and clinical implications of these findings are discussed

Spatio-Temporal Transmission Patterns of Black-Band Disease in a Coral Community

Transmission mechanisms of black-band disease (BBD) in coral reefs are poorly understood, although this disease is considered to be one of the most widespread and destructive coral infectious diseases. The major objective of this study was to assess transmission mechanisms of BBD in the field based on the spatio-temporal patterns of the disease

Prevalence of human papillomavirus antibodies in young female subjects in England

Sera from 1483 female subjects in England aged 10–29 years were tested. The age-standardised seroprevalence was 10.7% (95% confidence intervals 9.0–12.3) for human papillomavirus (HPV) 6, 2.7% (1.8–3.6) for HPV 11, 11.9% (10.2–13.6) for HPV 16, 4.7% (3.5–5.8) for HPV 18, and 20.7% (18.6–22.7) for any of the four types

A unifying mathematical framework for experimental TCR-pMHC kinetic constants

Receptor binding and triggering are central in Immunology as T cells activated through their T cell receptors (TCR) by protein antigens orchestrate immune responses. In order to understand receptor-ligand interactions, many groups working with different experimental techniques and assays have generated a vast body of knowledge during the last decades. However, in recent years a type of assays, referred to as two-dimensional or membrane-to-membrane, has questioned our current understanding of the role of different kinetic constants (for instance, on- versus off-rate constants) on TCR-ligand interaction and subsequent T cell activation. Here we present a general mathematical framework that provides a unifying umbrella to relate fundamental and effective (or experimentally determined) kinetic constants, as well as describe and compare state-of-the-art experimental methods. Our framework is able to predict the correlations between functional output, such as 1/EC50, and effective kinetic constants for a range of different experimental assays (in two and three dimensions). Furthermore, our approach can be applied beyond Immunology, and serve as a “translation method” for the biochemical characterization of receptor-ligand interactions

Understanding fear of opportunism in global prize-based science contests: Evidence for gender and age differences

Global prize-based science contests have great potential for tapping into diverse knowledge on a global scale and overcoming important scientific challenges. A necessary step for knowledge to be utilized in these contests is for that knowledge to be disclosed. Knowledge disclosure, however, is paradoxical in nature: in order for the value of knowledge to be assessed, inventors must disclose their knowledge, but then the person who receives that knowledge does so at no cost and may use it opportunistically. This risk of potential opportunistic behavior in turn makes the inventor fearful of disclosing knowledge, and this is a major psychological barrier to knowledge disclosure. In this project, we investigated this fear of opportunism in global prize-based science contests by surveying 630 contest participants in the InnoCentive online platform for science contests. We found that participants in these science contests experience fear of opportunism to varying degrees, and that women and older participants have significantly less fear of disclosing their scientific knowledge. Our findings highlight the importance of taking differences in such fears into account when designing global prize-based contests so that the potential of the contests for reaching solutions to important and challenging problems can be used more effectively

Measurement of the branching ratio of pi^0 -> e^+e^- using K_L -> 3 pi^0 decays in flight

The branching ratio of the rare decay pi^0 -> e^+e^- has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermilab. The pi^0's were produced in fully-reconstructed K_L -> 3 pi^0 decays in flight. We observed 275 candidate pi^0 -> e^+e^- events, with an expected background of 21.4 +- 6.2 events which includes the contribution from Dalitz decays. We measured BR(pi^0 -> e^+e^-, x>0.95) = (6.09 +- 0.40 +- 0.24) times 10^{-8}, where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound.Comment: New version shortened to PRL length limit. 5 pages, 4 figures. Published in Phys. Rev. Let