1,657 research outputs found

    Intracavity Dye-Laser Absorption Spectroscopy (IDLAS) for application to planetary molecules

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    Time-resolved, quasi-continuous wave, intracavity dye-laser absorption spectroscopy is applied to the investigation of absolute absorption coefficients for vibrational-rotational overtone bands of water at visible wavelengths. Emphasis is placed on critical factors affecting detection sensitivity and data analysis. Typical generation-time dependent absorption spectra are given

    First International Conference on Laboratory Research for Planetary Atmospheres

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    Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices

    Measurements of the methane relaxation times for application to the infrared emission models of the upper atmospheres of outer planets and Titan

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    The 7.8 micrometer emission from the nu(sub 4) band of methane (CH4) is a regularly observed feature in the stratosphere of all the giant planets and Titan. On Jupiter, enhancements in this emission are associated with the infrared hot spots in the auroral zone. Attempts to model this phenomenon in particular, and to understand the role of methane in general, have been hampered in part by a lack of adequate laboratory measurements of the collisional relaxation times for the nu(sub 3) and nu(sub 4) levels over the appropriate temperature range. To provide this needed data, a series of laboratory experiments were initiated. In the experimental arrangement the nu(sub3) band of methane is pumped at 3.3 micrometers using a pulsed infrared source (Nd:YAG/dye laser system equipped with a wave-length extender). The radiative lifetime of the nu(sub 3) level (approximately 37 ms) is much shorter than the nu(sub 4) lifetime (approximately 390 ms); however, a rapid V-V energy transfer rate ensures that the nu(sub 4) level is substantially populated. The photoacoustic technique is used to acquire relaxation rate information. The experiments are performed using a low-temperature, low-pressure cell. Experimental apparatus and technique are described. In addition some of the experimental difficulties associated with making these measurements are discussed and some preliminary results are presented

    Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing

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    Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed

    Vapor pressures of acetylene at low temperatures

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    The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data

    Cooperative Business Failures in Batangas Province, Philippines: A Postmortem Analysis

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    Cooperatives all over the world are said to be imbued with inherent weaknesses and challenges, and therefore, steering these entities towards sustainability is seen as an uphill climb. This paper delves into the reasons why some cooperatives in the Philippines dissolve or stop operating. Specifically, the study aimed to review the literature on factors affecting cooperative business sustainability and failures, to present and analyze two cases of failed multipurpose cooperatives and offer recommendations on operating cooperatives for their continued sustainability. Data was gathered through key informant interviews and secondary sources, and analyzed using the case approach and descriptive analysis. Extant literature primarily pinpointed issues such as poor management, lack of capital, property rights, and portfolio problems as the culprits behind cooperative conversions, failures and restructurings. What made the two multipurpose cooperatives unsustainable were the insufficiency of funds needed to meet Cooperatives Development Authority (CDA) requirements, delinquency of members and their inactive participation in cooperative affairs, mismanagement of resources, absence of a viable marketing system and the lack of a capable financial manager. Cultivating managerial and leadership skills, improving governance, establishing private sector and government linkages and support, encouraging participatory membership, utilizing an effective marketing system, proper resource management and expanding financial knowhow are suggested to achieve cooperative sustainability

    Evolution in the Disks and Bulges of Group Galaxies since z=0.4

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    We present quantitative morphology measurements of a sample of optically selected group galaxies at 0.3 < z < 0.55 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) and the GIM2D surface brightness--fitting software package. The group sample is derived from the Canadian Network for Observational Cosmology Field Redshift survey (CNOC2) and follow-up Magellan spectroscopy. We compare these measurements to a similarly selected group sample from the Millennium Galaxy Catalogue (MGC) at 0.05 < z < 0.12. We find that, at both epochs, the group and field fractional bulge luminosity (B/T) distributions differ significantly, with the dominant difference being a deficit of disk--dominated (B/T < 0.2) galaxies in the group samples. At fixed luminosity, z=0.4 groups have ~ 5.5 +/- 2 % fewer disk--dominated galaxies than the field, while by z=0.1 this difference has increased to ~ 19 +/- 6 %. Despite the morphological evolution we see no evidence that the group environment is actively perturbing or otherwise affecting the entire existing disk population. At both redshifts, the disks of group galaxies have similar scaling relations and show similar median asymmetries as the disks of field galaxies. We do find evidence that the fraction of highly asymmetric, bulge--dominated galaxies is 6 +/- 3 % higher in groups than in the field, suggesting there may be enhanced merging in group environments. We replicate our group samples at z=0.4 and z=0 using the semi-analytic galaxy catalogues of Bower et al (2006). This model accurately reproduces the B/T distributions of the group and field at z=0.1. However, the model does not reproduce our finding that the deficit of disks in groups has increased significantly since z=0.4.Comment: Accepted for publication in MNRAS. 20 pages, 17 figure

    Inhibiting ERK Activation with CI-1040 Leads to Compensatory Upregulation of Alternate MAPKs and Plasminogen Activator Inhibitor-1 following Subtotal Nephrectomy with No Impact on Kidney Fibrosis

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    Extracellular-signal regulated kinase (ERK) activation by MEK plays a key role in many of the cellular processes that underlie progressive kidney fibrosis including cell proliferation, apoptosis and transforming growth factor β1-mediated epithelial to mesenchymal transition. We therefore assessed the therapeutic impact of ERK1/2 inhibition using a MEK inhibitor in the rat 5/6 subtotal nephrectomy (SNx) model of kidney fibrosis. There was a twentyfold upregulation in phospho-ERK1/2 expression in the kidney after SNx in Male Wistar rats. Rats undergoing SNx became hypertensive, proteinuric and developed progressive kidney failure with reduced creatinine clearance. Treatment with the MEK inhibitor, CI-1040 abolished phospho- ERK1/2 expression in kidney tissue and prevented phospho-ERK1/2 expression in peripheral lymphocytes during the entire course of therapy. CI-1040 had no impact on creatinine clearance, proteinuria, glomerular and tubular fibrosis, and α-smooth muscle actin expression. However, inhibition of ERK1/2 activation led to significant compensatory upregulation of the MAP kinases, p38 and JNK in kidney tissue. CI-1040 also increased the expression of plasminogen activator inhibitor-1 (PAI-1), a key inhibitor of plasmin-dependent matrix metalloproteinases. Thus inhibition of ERK1/2 activation has no therapeutic effect on kidney fibrosis in SNx possibly due to increased compensatory activation of the p38 and JNK signalling pathways with subsequent upregulation of PAI-1
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