Superradiant lasing from J-aggregated molecules adsorbed onto colloidal silver

Cataloged from PDF version of article.The picosecond time-resolved emission spectrum of the cyanine dye 1,18-diethyl-3,38- bis-~3-sulfopropyl!-5,58,6,68-tetrachlorobenzimidazolocarbocyanine ~also known as BIC! adsorbed onto colloidal silver was examined as a function of laser pulse energy at room temperature. BIC is found to aggregate on colloidal silver, and the number of coherently responding molecules involved in the one-exciton state ~i.e., the coherence length! was estimated to involve 8–9 molecules. Lasing at a remarkably low incident pulse energy threshold was found for this system and explained in terms of a mechanism involving superradiant states created in coherently coupled adsorbed molecules that emit photons which stimulate emission from other spatially distributed superradiant states. © 1998 American Institute of Physics

Ice-sheet bed 3-D tomography

This is the published version. Copyright 2010 International Glaciological SocietyInformation on bed topography and basal conditions is essential to developing the next-generation ice-sheet models needed to generate a more accurate estimate of ice-sheet contribution to sea-level rise. Synthetic aperture radar (SAR) images of the ice–bed can be analyzed to obtain information on bed topography and basal conditions. We developed a wideband SAR, which was used during July 2005 to perform measurements over a series of tracks between the GISP2 and GRIP cores near Summit Camp, Greenland. The wideband SAR included an eight-element receive-antenna array with multiple-phase centers. We applied the MUltiple SIgnal Classification (MUSIC) algorithm, which estimates direction of arrival signals, to single-pass multichannel data collected as part of this experiment to obtain fine-resolution bed topography. This information is used for producing fine-resolution estimates of bed topography over a large swath of 1600m, with a 25m posting and a relative accuracy of approximately 10m. The algorithm-derived estimate of ice thickness is within 10m of the GRIP ice-core length. Data collected on two parallel tracks separated by 500m and a perpendicular track are compared and found to have difference standard deviations of 9.1 and 10.3m for the parallel and perpendicular tracks, respectively

Passing the Torch: Continuation of the South Carolina Libraries Journal

In this article, The South Carolina Libraries Editorial Board discusses the history and rebuilding of the South Carolina Libraries journal, the official publication of the South Carolina Library Association (SCLA). As the journal adjusted in response to community needs, changes in the Editorial Board, the publication cycle, and peer review process were made to expand and enhance the functionality, appearance, and content of the journal. The Editorial Board reviews strategies for library community members – including practitioners, research faculty, and LIS students – to become involved as a part of the publication through authoring, book reviewing, peer reviewing, or artwork for future issues

Pasture Management in the US Midwest – An Assessment of Current Practices and Future Opportunities

Managed grazing offers significant potential to improve the sustainability of livestock farms in the US Midwest, however the benefits of managed grazing are largely influenced by the management practices employed on farm. The objective of this study was to gain an understanding of current grazing practices on Midwest farms and to identify the knowledge and support needs of graziers. A total of 185 responses were received from a range of different enterprises including dairy, beef, and sheep production. Results show a substantial degree of variation in grazing management practices between respondents and highlights significant scope for improvement on farms particularly in the areas of pasture measurement and budgeting, and grazing infrastructure. Reported benefits of managed grazing included lower environmental impact, better pasture and animal performance, better animal health and welfare, and lower costs. Challenges with managed grazing included time and labor input, maintaining pasture quantity and quality during the grazing season, adverse weather conditions such as excessive rain and drought, and animal health challenges such as heat stress, parasites and in some cases coyotes. The study highlighted opportunities for research and extension providers to better support farmers with information and advice and identified knowledge gaps in areas such as pasture species selection, soil fertility, grazing infrastructure, pasture budgeting, legumes, and pasture measurement. The study successfully gained an insight into graziers in the Midwest, the outputs of which, will be valuable to a number of key stakeholders going forward, including researchers, extension agents, farmers and policy makers

Morphology of Dbx1 respiratory neurons in the preBotzinger complex and reticular formation of neonatal mice

The relationship between neuron morphology and function is a perennial issue in neuroscience. Information about synaptic integration, network connectivity, and the specific roles of neuronal subpopulations can be obtained through morphological analysis of key neurons within a microcircuit. Here we present morphologies of two classes of brainstem respiratory neurons. First, interneurons derived from Dbx1-expressing precursors (Dbx1 neurons) in the preBotzinger complex (preBotC) of the ventral medulla that generate the rhythm for inspiratory breathing movements. Second, Dbx1 neurons of the intermediate reticular formation that influence the motor pattern of pharyngeal and lingual movements during the inspiratory phase of the breathing cycle. We describe the image acquisition and subsequent digitization of morphologies of respiratory Dbx1 neurons from the preBotC and the intermediate reticular formation that were first recorded in vitro. These data can be analyzed comparatively to examine how morphology influences the roles of Dbx1 preBotC and Dbx1 reticular interneurons in respiration and can also be utilized to create morphologically accurate compartmental models for simulation and modeling of respiratory circuits

Cutaneous and Muscle Reactive Hyperemia in Young Adults with Major Depressive Disorder

The reactive hyperemic vasodilatory response to a brief period of tissue ischemia provides an index of microvascular function and is an independent predictor of cardiovascular morbidity and mortality. As such, reactive hyperemia is a non-invasive technique that is commonly utilized to provide an index of vascular health in various patient groups. Major depressive disorder (MDD), a non-traditional risk factor for cardiovascular disease (CVD), has been associated with blunted reactive hyperemia, though this is not a universal finding. Further, to date, the quantification of the reactive hyperemic response in adults with MDD has been limited to the forearm muscle, assessed as Doppler ultrasound derived blood velocity in the brachial artery following a period of suprasystolic cuff occlusion. PURPOSE: Here, we sought to more comprehensively assess microvascular reactive hyperemia in otherwise healthy young adults with MDD. We tested the hypothesis that both muscle and cutaneous vasodilation would be blunted in adults with MDD compared to non-depressed young adults. METHODS: Nine healthy adults (HA; age: 22±2 yrs: body mass index: 26.5 ± 1.8 kg/m2) and ten adults with MDD (non-medicated; age: 22±2 yrs: body mass index: 22.6 ± 4.4 kg/m2) participated. Forearm reactive hyperemia was assessed as the increase in blood velocity in the brachial artery following 5-min of suprasystolic cuff occlusion (distal to the olecranon process). In a subset of adults (n=5 HA; n=4 MDD), cutaneous reactive hyperemia was concurrently assessed via laser Doppler flowmetry-derived flux (perfusion units; PU). Peak and total (area-under-the-curve; AUC) reactive hyperemia were quantified for each methodological approach. RESULTS: Neither the brachial artery Doppler ultrasound-derived peak (HA: 1020±383 vs. MDD: 950±239 s-1; p=0.65) nor the total blood flow (HA: 284±77 vs. MDD: 233±153 a.u.; p=0.41) reactive hyperemic response was different between groups. Further, there were no group differences in cutaneous reactive hyperemia (peak: 83±37 HA vs. 79±15 PU MDD, p=0.85; AUC: 8764±2273 HA vs. 8935±1439 a.u. MDD; p=0.90). CONCLUSION: These preliminary data indicate that neither the muscle nor cutaneous vasodilatory response to a brief period of tissue ischemia is blunted in young adults with MDD, suggesting preserved microvascular function

Tromp1, a putative rare outer membrane protein, is anchored by an uncleaved signal sequence to the Treponema pallidum cytoplasmic membrane.

Treponema pallidum rare outer membrane protein 1 (Tromp1) has extensive sequence homology with substrate-binding proteins of ATP-binding cassette transporters. Because such proteins typically are periplasmic or cytoplasmic membrane associated, experiments were conducted to clarify Tromp1's physicochemical properties and cellular location in T. pallidum. Comparison of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobilities of (i) native Tromp1 and Tromp1 synthesized by coupled in vitro transcription-translation and (ii) native Tromp1 and recombinant Tromp1 lacking the N-terminal signal sequence revealed that the native protein is not processed. Other studies demonstrated that recombinant Tromp1 lacks three basic porin-like properties: (i) the ability to form aqueous channels in liposomes which permit the influx of small hydrophilic solutes, (ii) an extensive beta-sheet secondary structure, and (iii) amphiphilicity. Subsurface localization of native Tromp1 was demonstrated by immunofluorescence analysis of treponemes encapsulated in gel microdroplets, while opsonization assays failed to detect surface-exposed Tromp1. Incubation of motile treponemes with 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)-diazarine, a photoactivatable, lipophilic probe, also did not result in the detection of Tromp1 within the outer membranes of intact treponemes but, instead, resulted in the labeling of a basic 30.5-kDa presumptive outer membrane protein. Finally, analysis of fractionated treponemes revealed that native Tromp1 is associated predominantly with cell cylinders. These findings comprise a body of evidence that Tromp1 actually is anchored by an uncleaved signal sequence to the periplasmic face of the T. pallidum cytoplasmic membrane, where it likely subserves a transport-related function

Strong coupling between surface plasmon-polaritons and organic molecules in subwavelength hole arrays

J. Dintinger, S. Klein, F. Bustos, William L. Barnes, and T. W. Ebbesen, Physical Review B, Vol. 71, article 035424 (2005). "Copyright © 2005 by the American Physical Society."The interaction of a J-aggregate and surface plasmon polariton modes of a subwavelength hole array have been studied in detail. By measuring the effects of hole array period, angular dispersion and concentration of the J-aggregate on the transmission of the array, the existence of a strong coupling regime is demonstrated with a Rabi splitting of 250 meV. This large splitting is explained not only by the high oscillator strength of the dye but also by the high local field amplitudes generated by surface plasmons of the metallic structure

Invasive Lionfish Drive Atlantic Coral Reef Fish Declines

Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them

Biology and ecology of the invasive lionfishes, Pterois miles and Pterois volitans

The Indo-Pacific lionfishes, Pterois miles and P. volitans, are now established along the U.S. southeast coast, Bermuda, Bahamas, and are becoming established in the Caribbean. While these lionfish are popular in the aquarium trade, their biology and ecology are poorly understood in their native range. Given the rapid establishment and potential adverse impacts of these invaders, comprehensive studies of their biology and ecology are warranted. Here we provide a synopsis of lionfish biology and ecology including invasion chronology, taxonomy, local abundance, reproduction, early life history and dispersal, venomology, feeding ecology, parasitology, potential impacts, and control and management. This information was collected through review of the primary literature and published reports and by summarizing current observations. Suggestions for future research on invasive lionfish in their invaded regions are provided