Image spread in the infectious development of graphic arts film

The problem of this experiment is to determine which of three factors; sulfite level, bromine level, and development time, affect the image spreading during the infectious development of a graphic arts film. Three different levels of each factor will be studied. The method used consists of measuring the distance between two fine edges on a test target. This test target is then contact printed onto the graphic arts film. The distance between the two fine edges on the graphic arts film is then measured. Any difference between the two distances will be the result of image spreading. It is these distance differences that are used as the response in the three level, three factor Yates analysis. The sulfite level has been found to be a significant factor. The conclusion is that the sulfite concentration affects the image spreading during the infectious development of graphic arts film, but not bromine level or development time. The film tested was Kodak Kodalith Ortho, Type 3

Comparison of the cardiopharyngeal gene regulatory networks in Corella inflata and Ciona robusta provides insights into developmental systems drift

Mutations to gene regulatory networks drive evolutionary adaptation, but mutations can also occur without phenotypic change. These neutral mutations instead lead to developmental systems drift, evolutionary divergence in developmental systems that does not alter the traits produced. Here we examine developmental systems drift between two tunicate species, Corella inflata and Ciona robusta, in the cardiopharyngeal gene regulatory network. Through cross-species assays and functional enhancer analysis, we assess the amount of drift both in cis and in trans. Here we show that the trans-regulatory architecture of the cardiopharyngeal gene regulatory network is largely conserved between C. robusta and C. inflata, but cis-regulatory elements within this network exhibit distinct levels of conservation. These results suggest that the amount of drift cis-regulatory elements undergo is not governed by overarching principles but rather by distinct structural and functional constraints which are unique to each cis-regulatory element. We show that the enhancer for FoxF, a key cardiopharyngeal gene, is highly conserved and propose a model for the unique structural and functional constraints which this cis-regulatory element experiences

Laser-plasma interactions as tools for studying processes in quantum electrodynamics

Conventional particle accelerators and astronomical observations have long been some of the only tools for studying processes in high energy physics. The development of laser-plasma sources and high gradient accelerators will therefore be a key asset to these studies. In particular, laser-plasma accelerators have favourable spatial and temporal properties for studies into intense processes, and can be readily coupled to a wide array of other laser-plasma sources creating unique environments. Here, coupling to an X-ray source and intense laser focus were used to study processes in quantum electrodynamics. To study the linear Breit-Wheeler process, a 40 ps laser was used to drive a volumetric X-ray emitter. Line emission from a thin-foil Ge target, produced a highly efficient (3.4%), dense source of 1.3 − 1.9 keV X-rays, with 3 ± 1 (stat.) ±0.4 (sys.) ×10^{12} photons/eV/sphere. These X-rays were collided with bremsstrahlung gamma rays (with energies up to 800 MeV) to investigate electron-positron pair production. The X-ray source was well-optimised for studying this interaction, and would allow the detection of Breit-Wheeler pairs if used with a moderately improved electron beam for generating bremsstrahlung (3× the highest electron energy and 5× the total charge, as achieved previously). This would constitute the first laser-plasma photon- photon collider with low virtuality (energy off mass-shell ≈ 10^{−20} MeV^2). In order to differentiate between competing models of electron radiation reaction in strong field quantum electrodynamics, a narrow energy-spread electron beam was studied. By utilising shock injection into a laser wakefield accelerator, a high energy (1260±40 MeV), narrow energy- spread (4.1±0.9 %) beam was generated. This is one of only a few studies that have successfully achieved these electron beam properties. While the shot-to-shot reproducibility of the electron beam was limited to 60%, the relative energy-spread was sufficiently small that differentiation of radiation reaction models could be readily achieved in future experiments. With the upcoming commissioning of many multi-PW laser facilities, these studies demonstrate how active research into quantum electrodynamics can be achieved on the smaller, more accessible, laser-laboratory scale.Open Acces

The abandoned ice sheet base at Camp Century, Greenland, in a warming climate

In 1959 the U.S. Army Corps of Engineers built Camp Century beneath the surface of the northwestern Greenland Ice Sheet. There they studied the feasibility of deploying ballistic missiles within the ice sheet. The base and its wastes were abandoned with minimal decommissioning in 1967, under the assumption they would be preserved for eternity by perpetually accumulating snowfall. Here we show that a transition in ice sheet surface mass balance at Camp Century from net accumulation to net ablation is plausible within the next 75 years, under a business-as-usual anthropogenic emissions scenario (Representative Concentration Pathway 8.5). Net ablation would guarantee the eventual remobilization of physical, chemical, biological, and radiological wastes abandoned at the site. While Camp Century and four other contemporaneous ice sheet bases were legally established under a Danish-U.S. treaty, the potential remobilization of their abandoned wastes, previously regarded as sequestered, represents an entirely new pathway of political dispute resulting from climate change

Inland dunes on the abandoned bed of Glacial Lake Chicago indicate eolian activity during the Pleistocene-Holocene transition, southwestern Michigan, USA

Inland dune fields have recently emerged as a source of data for reconstructing paleoenvironments and climate in the western Great Lakes region of North America during the Pleistocene-Holocene transition. We employ optically stimulated luminescence (OSL) methods, radiocarbon ages, soils, and landform relationships to determine the age of inland dunes in Ottawa County, Michigan. These dunes rest on the abandoned bed of Glacial Lake Chicago, which is thought to have been exposed after ~13.6 ka. OSL analyses from two inland dunes yield ages ranging from 13.3±1.1 to 11.6±0.9 ka (uncertainty = 2 σ). Fine sand in the parabolic dunes suggests deflation of exposed glaciolacustrine nearshore sand by northwesterly and westerly winds. These new data add to a growing number of studies that demonstrate widespread eolian activity in the western Great Lakes region during the Pleistocene-Holocene transition. OSL ages from dune fields in the western Great Lakes indicate peak eolian activity and dune stabilization occurred during or following the Younger Dryas and Preboreal events. Northwesterly and westerly winds suggest the limited effect of hypothesized easterly anticyclonic winds during the Pleistocene-Holocene transition. Rapidly changing climate and newly deglaciated surfaces provided an ideal environment for dune formation

Open-Pit Glacier Ice Excavation: Brief Review

Abstract: The authors have compiled information on the fundamentals of open-pit glacier ice excavation from a variety of sources. These sources primarily include U.S. Army technical and scientific studies and peer-reviewed research on glacier ice-excavation activities and the properties and mechanical behavior of ice, but also the relatively few publicly available feasibility studies and environmental impact assessments published by private mining companies. While ice is technically a non-Newtonian fluid over long timescales, the authors suggest that it may be regarded as a low-density and low-strength rock, analogous to coal, for the practical purpose of ice excavation over short timescales. Three distinct ice-excavation techniques are reviewed: blasting, melting, and mechanical excavation, providing a case study of each. The authors summarize the unique advantages and disadvantages of each technique and conclude that an optimal open-ice-pit mining operation would most likely rely primarily on mechanical excavation and secondarily on blasting

NOTES AND CORRESPONDENCE On the Use of Slow Ascent Meter-Scale Sampling (SAMS) Radiosondes for Observing Overturning Events in the Free Atmosphere

ABSTRACT This note describes the development of a method for obtaining high vertical resolution (meter scale) measurements of basic meteorological quantities and turbulent overturns, using radiosondes with slow ascent rates. Although the method has some limitations, it can provide profiles of standard atmospheric variables from the surface to more than 20 km, with significantly improved vertical resolution. It can also help better identify regions of turbulent overturns. This correspondence presents some initial results demonstrating the occurrence of relatively small-vertical-scale overturns throughout the entire atmospheric column

Circum-Greenland, ice-thickness measurements collected during PROMICE airborne surveys in 2007, 2011 and 2015

The Greenland ice sheet has experienced an average mass loss of 142 ± 49 Gt/yr from 1992 to 2011 (Shepherd et al. 2012), making it a significant contributor to sea-level rise. Part of the ice- sheet mass loss is the result of increased dynamic response of outlet glaciers (Rignot et al. 2011). The ice discharge from outlet glaciers can be quantified by coincident measurements of ice velocity and ice thickness (Thomas et al. 2000; van den Broeke et al. 2016). As part of the Programme for monitoring of the Greenland Ice Sheet (PROMICE; Ahlstrøm et al. 2008), three airborne surveys were carried out in 2007, 2011 and 2015, with the aim of measuring the changes in Greenland ice-sheet thicknesses. The purpose of the airborne surveys was to collect data to assess the dynamic mass loss of the Greenland ice sheet (Andersen et al. 2015). Here, we present these datasets of observations from ice-penetrating radar and airborne laser scanning, which, in combination, make us able to determine the ice thickness precisely. Surface-elevation changes between surveys are also presented, although we do not provide an in-depth scientific interpretation of these