Different forms of the bovine PrP gene have five or six copies of a short, G-C-rich element within the protein-coding exon

Current models of the virus-like agents of scrapie and bovine spongiform encephalopathy (BSE) have to take into account that structural changes in a host-encoded protein (PrP protein) exhibit an effect on the time course of these diseases and the survival time of any man or animal exposed to these pathogens. We report here the sequence of different forms of the bovine PrP gene which contain either five or six copies of a short, G-C-rich element which encodes the octapeptide Pro-His-Gly-Gly-Gly-Trp-Gly-Gln or its longer variants Pro-Gln/His-Gly-Gly-Gly-Gly-Trp-Gly-Gln. Out of 12 cattle, we found eight animals homozygous for genes with six copies of the Gly-rich peptide (6:6), while four were heterozygous (6:5). Two confirmed cases of BSE occurred in (6: 6) homozygous animals. Bovine spongiform encephalopathy (BSE) is a transmissible disease (Fraser et al., 1988; Dawson et al., 1990; Barlow & Middleton, 1990) which produces neuropathological lesions in cattle similar to those seen in ovine scrapie (Wells et al., 1987) and the rare human dementias Creutzfeldt-Jakob disease (CJD) and Gerstmann-Str/iussler syndrome (GSS) (Beck & Daniel, 1987). A cellular membrane protein (PrP) has a key role in the transmission and development of these diseases. This protein accumulates in the brain and other tissues during the protracted time course of these diseases and, in a disease-specific, protease-resistant isoform (SAF-PrP), has been purified by subcellular fractionation of scrapie

The Everyday Universe

I take inspiration from ordinary objects and materials. Through photography, I attempt to transcend the familiar to discover complexity within the bits and pieces of my everyday life. Like other artistic representations, a photograph is a singular portrayal, not an actualization of physical reality. My artistic exploration of this involves incorporating elements of abstraction to point to the truth that all photographs are, by nature, an abstraction of our physical reality based on perspective. The resulting images often share a quality of impermanence, counterbalanced by the act of making a photographic document. By evoking this temporal quality of photography and abstracting familiar materials and surfaces, I aim to create a playful tension in my imagery

Errors in pigeons\u27 memory for number: Effects of ITI and DI illumination

In Experiment 1 all pigeons were trained to discriminate 2 flashes of hopper light in 4 sec from 8 flashes in 4 sec, at a 0 sec delay. One group of pigeons experienced dark lTl’s (Group Dark) while the other experienced an illuminated lTl (Group Light). All birds were then tested with dark delays of 0, 5, 10, 15, and 20 sec. Analysis showed a significant bias to respond to the comparison correct for small at extended delays, with no difference between groups. In Experiment 2 training was identical to that in Experiment l except that a 5 sec baseline delay was used. The pigeons were then tested at delays of 0, 5, 10, 15, and 20 sec. Again, analysis showed a tendency to choose the comparison correct for small at delays longer than baseline, while at delays shorter than baseline they showed a bias to respond large. No group differences were observed. In Experiment 3, an illuminated Dl was introduced for both groups. Analysis showed a reversal of the biases observed in Experiment 2. At delays longer than baseline a choose-large bias occurred, while at delays shorter than baseline a choose-small bias was observed. Again, there were no group differences. It was hypothesized that illuminating the Dl added pulse counts to the pigeons’ memory for the samples, suggesting that an event switch was not being used, but that the total amount of light in each trial was being summed. The results are clearly inconsistent with the contusion hypothesis and support a subjective shortening account of memory biases for temporal discriminations. However, whether this theory can be extended to include a subjective shrinking of number remains in question

Generating controllable atom-light entanglement with a Raman atom laser system

We introduce a scheme for creating continuous variable entanglement between an atomic beam and an optical field, by using squeezed light to outcouple atoms from a BEC via a Raman transition. We model the full multimode dynamics of the atom laser beam and the squeezed optical field, and show that with appropriate two-photon detuning and two-photon Rabi frequency, the transmitted light is entangled in amplitude and phase with the outcoupled atom laser beam. The degree of entanglement is controllable via changes in the two-photon Rabi frequency of the outcoupling process.Comment: 4 pages, 4 figure

The Everyday Universe

I take inspiration from ordinary objects and materials. Through photography, I attempt to transcend the familiar to discover complexity within the bits and pieces of my everyday life. Like other artistic representations, a photograph is a singular portrayal, not an actualization of physical reality. My artistic exploration of this involves incorporating elements of abstraction to point to the truth that all photographs are, by nature, an abstraction of our physical reality based on perspective. The resulting images often share a quality of impermanence, counterbalanced by the act of making a photographic document. By evoking this temporal quality of photography and abstracting familiar materials and surfaces, I aim to create a playful tension in my imagery

Pulse retrieval and soliton formation in a non-standard scheme for dynamic electromagnetically induced transparency

We examine in detail an alternative method of retrieving the information written into an atomic ensemble of three-level atoms using electromagnetically induced transparency. We find that the behavior of the retrieved pulse is strongly influenced by the relative collective atom-light coupling strengths of the two relevant transitions. When the collective atom-light coupling strength for the retrieval beam is the stronger of the two transitions, regeneration of the stored pulse is possible. Otherwise, we show the retrieval process can lead to creation of soliton-like pulses.Comment: 11 figure