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We present photometric observations of an apparent Type Ia supernova (SN Ia) at a redshift of D1.7, the farthest SN observed to date. The supernova, SN 1997 †, was discovered in a repeat observation by the Hubble Space T elescope (HST) of the Hubble Deep Field-North (HDF-N) and serendipitously monitored with NICMOS on HST throughout the Thompson et al.(More)
We have measured the rest-frame B, V, and I-band light curves of a high-redshift type Ia supernova (SN Ia), SN 1999Q (z = 0.46), using HST and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, E B−I , which is a sensitive indicator of interstellar or intergalactic dust which could affect recent cosmological(More)
Escherichia coli grows over a wide range of pHs (pH 4.4 to 9.2), and its own metabolism shifts the external pH toward either extreme, depending on available nutrients and electron acceptors. Responses to pH values across the growth range were examined through two-dimensional electrophoresis (2-D gels) of the proteome and through lac gene fusions. Strain(More)
We present constraints on the dark energy equation-of-state parameter, w = P/(ρc 2), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE su-pernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on (Ω M , w) from baryon acoustic oscillations, we obtain a value for a static(More)
We present multi-color optical and two-frequency radio observations of the bright SAX event, GRB 990510. The well-sampled optical decay, and the radio observations are both inconsistent with simple spherical afterglow models. The achromatic optical steepening and the decay of the radio afterglow both occuring at t ∼ 1 day are evidence for hydrodynamical(More)
Human-robot interfaces for interacting with hundreds of autonomous robots must be very different from single-robot interfaces. The central design challenge is developing techniques to maintain, program, and interact with the robots without having to handle them individually. This requires robots that can support hands-free operation, which drives many other(More)
The High-Z Supernova Search is an international collaboration to discover and monitor type Ia supernovae (SN Ia) at z > 0.2 with the aim of measuring cosmic deceleration and global curvature. Our collaboration has pursued a basic understanding of supernovae in the nearby Universe, discovering and observing a large sample of objects, and developing methods(More)
Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z approximately 20, and therefore to be powerful probes of the early Universe. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event(More)
We present ground-based optical observations of GRB 020124 starting 1.6 hours after the burst, as well as subsequent Very Large Array (VLA) and Hubble Space Telescope (HST) observations. The optical after-glow of GRB 020124 is one of the faintest afterglows detected to date, and it exhibits a relatively rapid decay, F ν ∝ t −1.60±0.04 , followed by further(More)
Scrapie can be transmitted by novel infectious pathogens termed prions. No evidence for a scrapie-specific nucleic acid has been detected to date. To investigate amounts, types and sizes of nucleic acid molecules associated with prions in purified preparations, aliquots were deproteinized, and the nucleic acids analysed by PAGE and silver staining.(More)