Aquatic Vegetation, Largemouth Bass and Water Quality Responses to Low-Dose Fluridone Two Years Post Treatment

Whole-lake techniques are increasingly being used to selectively remove exotic plants, including Eurasian watermilfoil ( Myriophyllum spicatum L.). Fluridone (1-methyl-3-phenyl- 5-[3-(trifluoromethyl)phenyl]-4(1 H )-pyridinone), a systemic whole-lake herbicide, is selective for Eurasian watermilfoil within a narrow low concentration range. Because fluridone applications have the potential for large effects on plant assemblages and lake food webs, they should be evaluated at the whole-lake scale. We examined effects of low-dose (5 to 8 ppb) fluridone applications by comparing submersed plant assemblages, water quality and largemouth bass ( Micropterus salmoides ) growth rates and diets between three reference lakes and three treatment lakes one- and two-years post treatment. In the treatment lakes, fluridone reduced Eurasian watermilfoil cover without reducing native plant cover, although the duration of Eurasian watermilfoil reduction varied among treatment lakes. (PDF has 11 pages.

Reanalysis of Copernicus Measurements on Interstellar Carbon Monoxide

We used archival data acquired with the Copernicus satellite to reexamine CO column densities because self-consistent oscillator strengths are now available. Our focus is on lines of sight containing modest amounts of molecular species. Our resulting column densities are small enough that self-shielding from photodissociation is not occurring in the clouds probed by the observations. While our sample shows that the column densities of CO and H2 are related, no correspondence with the CH column density is evident. The case for the CH+ column density is less clear. Recent chemical models for these sight lines suggest that CH is mainly a by-product of CH+ synthesis in low density gas. The models are most successful in reproducing the amounts of CO in the densest sight lines. Thus, much of the CO absorption must arise from denser clumps along the line of sight to account for the trend with H2.Comment: 19 pages, 6 figures. Accepted for publication in Ap

Research on nonlinear optical materials: an assessment. IV. Photorefractive and liquid crystal materials

This panel considered two separate subject areas: photorefractive materials used for nonlinear optics and liquid crystal materials used in light valves. Two related subjects were not considered due to lack of expertise on the panel: photorefractive materials used in light valves and liquid crystal materials used in nonlinear optics. Although the inclusion of a discussion of light valves by a panel on nonlinear optical materials at first seems odd, it is logical because light valves and photorefractive materials perform common functions

Fostering Organizational Integrity through Departmental Program Reviews

Conducting a departmental program review can be a stressful and arduous process. At the same time, the final report can provide valuable insights. The challenges and benefits of program reviews have been well noted by scholars. We seek to add to this conversation by arguing that program reviews can prove beneficial by fostering and maintaining organizational integrity. In our essay, we review relevant literature on program reviews, provide an explanation of organizational integrity, present a narrative of our program review process, and explain how this process fostered organizational integrity

The Canada-UK Deep Submillimetre Survey: The Survey of the 14-hour field

We have used SCUBA to survey an area of 50 square arcmin, detecting 19 sources down to a 3sigma sensitivity limit of 3.5 mJy at 850 microns. We have used Monte-Carlo simulations to assess the effect of source confusion and noise on the SCUBA fluxes and positions, finding that the fluxes of sources in the SCUBA surveys are significantly biased upwards and that the fraction of the 850 micron background that has been resolved by SCUBA has been overestimated. The radio/submillmetre flux ratios imply that the dust in these galaxies is being heated by young stars rather than AGN. We have used simple evolution models based on our parallel SCUBA survey of the local universe to address the major questions about the SCUBA sources: (1) what fraction of the star formation at high redshift is hidden by dust? (2) Does the submillimetre luminosity density reach a maximum at some redshift? (3) If the SCUBA sources are proto-ellipticals, when exactly did ellipticals form? However, we show that the observations are not yet good enough for definitive answers to these questions. There are, for example, acceptable models in which 10 times as much high-redshift star formation is hidden by dust as is seen at optical wavelengths, but also acceptable ones in which the amount of hidden star formation is less than that seen optically. There are acceptable models in which very little star formation occurred before a redshift of three (as might be expected in models of hierarchical galaxy formation), but also ones in which 30% of the stars have formed by this redshift. The key to answering these questions are measurements of the dust temperatures and redshifts of the SCUBA sources.Comment: 41 pages (latex), 17 postscript figures, to appear in the November issue of the Astronomical Journa

Generation of Ultrastable Microwaves via Optical Frequency Division

There has been increased interest in the use and manipulation of optical fields to address challenging problems that have traditionally been approached with microwave electronics. Some examples that benefit from the low transmission loss, agile modulation and large bandwidths accessible with coherent optical systems include signal distribution, arbitrary waveform generation, and novel imaging. We extend these advantages to demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. This provides a 10 GHz electrical signal with fractional frequency instability <8e-16 at 1 s, a value comparable to that produced by the best microwave oscillators, but without the need for cryogenic temperatures. Such a low-noise source can benefit radar systems, improve the bandwidth and resolution of communications and digital sampling systems, and be valuable for large baseline interferometry, precision spectroscopy and the realization of atomic time

Anaerobic Respiration of \u3cem\u3eEscherichia coli\u3c/em\u3e in the Mouse Intestine

The intestine is inhabited by a large microbial community consisting primarily of anaerobes and, to a lesser extent, facultative anaerobes, such as Escherichia coli, which we have shown requires aerobic respiration to compete successfully in the mouse intestine (S. A. Jones et al., Infect. Immun. 75:4891-4899, 2007). If facultative anaerobes efficiently lower oxygen availability in the intestine, then their sustained growth must also depend on anaerobic metabolism. In support of this idea, mutants lacking nitrate reductase or fumarate reductase have extreme colonization defects. Here, we further explore the role of anaerobic respiration in colonization using the streptomycin-treated mouse model. We found that respiratory electron flow is primarily via the naphthoquinones, which pass electrons to cytochrome bd oxidase and the anaerobic terminal reductases. We found that E. coli uses nitrate and fumarate in the intestine, but not nitrite, dimethyl sulfoxide, or trimethylamine N-oxide. Competitive colonizations revealed that cytochrome bd oxidase is more advantageous than nitrate reductase or fumarate reductase. Strains lacking nitrate reductase outcompeted fumarate reductase mutants once the nitrate concentration in cecal mucus reached submillimolar levels, indicating that fumarate is the more important anaerobic electron acceptor in the intestine because nitrate is limiting. Since nitrate is highest in the absence of E. coli, we conclude that E. coli is the only bacterium in the streptomycin-treated mouse large intestine that respires nitrate. Lastly, we demonstrated that a mutant lacking the NarXL regulator (activator of the NarG system), but not a mutant lacking the NarP-NarQ regulator, has a colonization defect, consistent with the advantage provided by NarG. The emerging picture is one in which gene regulation is tuned to balance expression of the terminal reductases that E. coli uses to maximize its competitiveness and achieve the highest possible population in the intestine

Revisiting the 'Missing Middle' in English Sub-National Governance

In the light of the new Coalition Government’s proposed ‘rescaling’ of sub-national governance away from the regional level, it is an opportune time to re-consider the strength and weaknesses of the city or sub-regional approach to economic development and to search, once more, for the ‘missing middle’ in English Governance. In this context, the article initially assesses the case for city or sub regions as tiers of economic governance, before examining the lessons to be learnt from the experiences of the existing city regions in the North East of England. It argues that while contemporary plans to develop Local Enterprise Partnerships (LEPs) can be usefully considered within the context of the emerging city regional developments under the previous Labour Governments, a number of important challenges remain, particularly in relation to ensuring accountable structures of governance, a range of appropriate functions, adequate funding, and comprehensive coverage across a variety of sub-regional contexts. While the proposals of the new Government create the necessary ‘space’ to develop sub-regional bodies and offer genuine opportunities for both city and county LEPs, the scale of the sub-regional challenge should not be underestimated, particularly given the context of economic recession and major reductions in the public sector