On Ptolemaic metric simplicial complexes

We show that under certain mild conditions, a metric simplicial complex which satisfies the Ptolemy inequality is a CAT(0) space. Ptolemy's inequality is closely related to inversions of metric spaces. For a large class of metric simplicial complexes, we characterize those which are isometric to Euclidean space in terms of metric inversions.Comment: 13 page

Complex surfaces plated by thin-film deposition in one operation

Ion plating deposits thin film on complex surface in one operation. The ionized materials follow electric lines of force to all points on the objects, uniformly plating the surface from all sides simultaneously

Implications of Alternative Emission Trading Plans: Experimental Evidence

Two approaches to emissions trading are cap-and-trade, in which an aggregate cap on emissions is distributed in the form of emission allowances and baseline-and-credit, in which firms earn emission reduction credits for emissions below their baselines. Theoretical considerations suggest the long-run equilibria of the two plans will differ if baselines are proportional to output, because a variable baseline is equivalent to an output subsidy. To test this prediction we have developed a computerized environment in which subjects representing firms can adjust both their emission rates (per unit output) and capacity levels. Subjects buy or sell emission rights (allowances or credits) in a sealed bid call auction. The demand for output is simulated. All decisions are tracked through a double-entry bookkeeping system. This environment is to be used to compare short and long run responses to the alternative trading methods. Initial experiments in this environment will alternately hold emission rate and capacity choice constant. We report on six experimental sessions with variable emissions rates but fixed capacity and two pilot sessions with variable capacity but fixed emission rates.

Optical studies of two LMC X-ray transients : RX J0544.1-7100 and RX J0520.5-6932

We report observations which confirm the identities of the optical counterpart to the transient sources RX J0544.1-7100 and RX J0520.5-6932. The counterparts are suggested to be a B-type stars. Optical data from the observations carried out at ESO and SAAO, together with results from the OGLE data base, are presented. In addition, X-ray data from the RXTE all-sky monitor are investigated for long term periodicities. A strong suggestion for a binary period of 24.4d is seen in RX J0520.5-6932 from the OGLE data.Comment: 6 pages, 7 figure

Five year prognosis in patients with angina identified in primary care : incident cohort study

Peer reviewedPublisher PD

Inverse scattering approach to multiwavelength Fabry-Pérot laser design

A class of multiwavelength Fabry-Pérot lasers is introduced where the spectrum is tailored through a patterning of the cavity effective index. The cavity geometry is obtained using an inverse scattering approach and can be designed such that the spacing of discrete Fabry-Pérot lasing modes is limited only by the bandwidth of the inverted gain medium. A specific two-color semiconductor laser with a mode spacing in the THz region is designed, and measurements are presented demonstrating the simultaneous oscillation of the two wavelengths. The nonperiodic effective index profile of the particular two-color device considered is shown to be related to a Moiré or superstructure grating

Replication enhancer elements within the open reading frame of tick-borne encephalitis virus and their evolution within the Flavivirus genus

We provide experimental evidence of a replication enhancer element (REE) within the capsid gene of tick-borne encephalitis virus (TBEV, genus Flavivirus). Thermodynamic and phylogenetic analyses predicted that the REE folds as a long stable stem–loop (designated SL6), conserved among all tick-borne flaviviruses (TBFV). Homologous sequences and potential base pairing were found in the corresponding regions of mosquito-borne flaviviruses, but not in more genetically distant flaviviruses. To investigate the role of SL6, nucleotide substitutions were introduced which changed a conserved hexanucleotide motif, the conformation of the terminal loop and the base-paired dsRNA stacking. Substitutions were made within a TBEV reverse genetic system and recovered mutants were compared for plaque morphology, single-step replication kinetics and cytopathic effect. The greatest phenotypic changes were observed in mutants with a destabilized stem. Point mutations in the conserved hexanucleotide motif of the terminal loop caused moderate virus attenuation. However, all mutants eventually reached the titre of wild-type virus late post-infection. Thus, although not essential for growth in tissue culture, the SL6 REE acts to up-regulate virus replication. We hypothesize that this modulatory role may be important for TBEV survival in nature, where the virus circulates by non-viraemic transmission between infected and non-infected ticks, during co-feeding on local rodents