Observation of erythrocyte dynamics in the retinal capillaries and choriocapillaris using ICG-loaded erythrocyte ghost cells.

Purpose To find evidence of retinal vasomotion and to examine the relationship between erythrocyte dynamics and previously observed high-frequency pulsatile blood flow through the choriocapillaris. Methods An osmotic shock technique was used to encapsulate indocyanine green (ICG) dye in erythrocyte ghost cells at a concentration that produced maximum cell fluorescence. By obviating the plasma staining that results from aqueous ICG's high affinity for plasma proteins, high contrast was maintained between reinjected ICG-loaded erythrocytes and their plasma background. High-speed, high-magnification ICG angiograms showing individual cell movement were recorded from the intact eyes of four monkeys and three rabbits for periods up to 30 seconds. Results In monkey retinal perifoveal capillaries, numerous erythrocytes were seen to pause for as long as 20 seconds and then resume transit. Similar pausing behavior was observed in the subfoveal choriocapillaris. Individual erythrocytes also were seen to pause in the rabbits' choriocapillaries below the medullary rays, where visualization of the cells was uninhibited by overlying retinal vasculature or dense pigment. Conclusions Reinjected ICG-loaded erythrocytes permit routine visualization of retinal capillary and choriocapillaris hemodynamics of the intact eye. It is speculated that erythrocyte-pausing in both microcirculations facilitates metabolic exchange across capillary walls. In retinal capillaries, pausing is presumed to result from vasomotion-which has been postulated as necessary for the inhibition of retinal edema-and in choriocapillaries, to result from the shifting distributions of local perfusion pressures within the network of capillary vessel segments that comprise each lobular area of the choriocapillaris vascular plexus

Comparative Absorption and Emission Abundance Analyses of Nebulae: Ion Emission Densities for IC 418

Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with column densities derived from resonance absorption lines viewed against the central star continuum. Separate analyses of the nebular emission lines and the stellar UV absorption lines yield independent abundances for ions, and their ratio can be expressed in terms of a parameter n_e_{em}, the ``emission density'' for each ion. Adequate data for this technique are still scarce, but separate analyses of spectra of the planetary nebula and central star of IC 418 do show discrepant abundances for several ions, especially Fe II. The discrepancies are probably due to the presence of absorbing gas which does not emit and/or to uncertain atomic data and excitation processes, and they demonstrate the importance of applying the technique of combining emission- and absorption-line data in deriving abundances for nebulae.Comment: 25 pages, 3 figures, accepted for publication in PAS

Re-Shuffling of Species with Climate Disruption: A No-Analog Future for California Birds?

By facilitating independent shifts in species' distributions, climate disruption may result in the rapid development of novel species assemblages that challenge the capacity of species to co-exist and adapt. We used a multivariate approach borrowed from paleoecology to quantify the potential change in California terrestrial breeding bird communities based on current and future species-distribution models for 60 focal species. Projections of future no-analog communities based on two climate models and two species-distribution-model algorithms indicate that by 2070 over half of California could be occupied by novel assemblages of bird species, implying the potential for dramatic community reshuffling and altered patterns of species interactions. The expected percentage of no-analog bird communities was dependent on the community scale examined, but consistent geographic patterns indicated several locations that are particularly likely to host novel bird communities in the future. These no-analog areas did not always coincide with areas of greatest projected species turnover. Efforts to conserve and manage biodiversity could be substantially improved by considering not just future changes in the distribution of individual species, but including the potential for unprecedented changes in community composition and unanticipated consequences of novel species assemblages

Albert Pierrepoint and the cultural persona of the twentieth-century hangman

Albert Pierrepoint was Britain’s most famous 20th-century hangman. This article utilises diverse sources in order to chart his public representation, or cultural persona, as hangman from his rise to prominence in the mid-1940s to his portrayal in the biopic Pierrepoint(2005). It argues that Pierrepoint exercised agency in shaping this persona through publishing his autobiography and engagement with the media, although there were also representations that he did not influence. In particular, it explores three iterations of his cultural persona – the Professional Hangman, the Reformed Hangman and the Haunted Hangman. Each of these built on and reworked historical antecedents and also communicated wider understandings and contested meanings in relation to capital punishment. As a hangman who remained in the public eye after the death penalty in Britain was abolished, Pierrepoint was an important, authentic link to the practice of execution and a symbolic figure in debates over reintroduction. In the 21st century, he was portrayed as a victim of the ‘secondary trauma’ of the death penalty, which resonated with worldwide campaigns for abolition

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead