N and Fe-Peak Elemental Abundances from IUE Co-Added Spectra of Hg-Mn and Normal Stars

AbstractLeckrone and Adelman have established an IUE observing strategy that has yielded co-added spectra with enhanced S/N ratios for several A and B stars. New observations by Roby and Adelman using the same technique have added two new Hg-Mn stars into this sample. We have begun a long-term study of elemental abundances in this uniform, high-quality set of IUE spectra for 13 stars. We report on the first stages of this project: abundances for N, Cr, Mn, Fe, Co, and Ni. The study of the Fe- peak elements show that our data set can provide accurate abundances and that abundances obtained from UV and optical spectra often are in good agreement. This study provides the groundwork for self-consistent abundance analyses of more exotic elements in our long term project.

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A long-term study of cloud residuals from low-level Arctic clouds

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-8933-2021 ◽

2021 ◽

Vol 21 (11) ◽

pp. 8933-8959

Author(s):

Linn Karlsson ◽

Radovan Krejci ◽

Makoto Koike ◽

Kerstin Ebell ◽

Paul Zieger

Keyword(s):

Cloud Formation ◽

Potential Contribution ◽

Size Distributions ◽

Term Study ◽

Inlet System ◽

Data Set ◽

Minimum Concentration ◽

Low Level ◽

Long Term Study

Abstract. To constrain uncertainties in radiative forcings associated with aerosol–cloud interactions, improved understanding of Arctic cloud formation is required, yet long-term measurements of the relevant cloud and aerosol properties remain sparse. We present the first long-term study of cloud residuals, i.e. particles that were involved in cloud formation and cloud processes, in Arctic low-level clouds measured at Zeppelin Observatory, Svalbard. To continuously sample cloud droplets and ice crystals and separate them from non-activated aerosol, a ground-based counter-flow virtual impactor inlet system (GCVI) was used. A detailed evaluation of the GCVI measurements, using concurrent cloud particle size distributions, meteorological parameters, and aerosol measurements, is presented for both warm and cold clouds, and the potential contribution of sampling artefacts is discussed in detail. We find an excellent agreement of the GCVI sampling efficiency of liquid clouds using two independent approaches. The 2-year data set of cloud residual size distributions and number concentrations reveals that the cloud residuals follow the typical seasonal cycle of Arctic aerosol, with a maximum concentration in spring and summer and a minimum concentration in the late autumn and winter months. We observed average activation diameters in the range of 58–78 nm for updraught velocities below 1 m s−1. A cluster analysis also revealed cloud residual size distributions that were dominated by Aitken mode particles down to around 20–30 nm. During the winter months, some of these small particles may be the result of ice, snow, or ice crystal shattering artefacts in the GCVI inlet; however, cloud residuals down to 20 nm in size were also observed during conditions when artefacts are less likely.

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Building the COllaborative Carbon Column Observing Network (COCCON): long-term stability and ensemble performance of the EM27/SUN Fourier transform spectrometer

Atmospheric Measurement Techniques ◽

10.5194/amt-12-1513-2019 ◽

2019 ◽

Vol 12 (3) ◽

pp. 1513-1530 ◽

Cited By ~ 15

Author(s):

Matthias Frey ◽

Mahesh K. Sha ◽

Frank Hase ◽

Matthäus Kiel ◽

Thomas Blumenstock ◽

...

Keyword(s):

Standard Deviation ◽

Total Carbon ◽

Data Sets ◽

Term Study ◽

Data Set ◽

Term Stability ◽

Long Term Stability ◽

Long Term Study ◽

Empirical Calibration

Abstract. In a 3.5-year long study, the long-term performance of a mobile, solar absorption Bruker EM27/SUN spectrometer, used for greenhouse gas observations, is checked with respect to a co-located reference Bruker IFS 125HR spectrometer, which is part of the Total Carbon Column Observing Network (TCCON). We find that the EM27/SUN is stable on timescales of several years; the drift per year between the EM27/SUN and the official TCCON product is 0.02 ppmv for XCO2 and 0.9 ppbv for XCH4, which is within the 1σ precision of the comparison, 0.6 ppmv for XCO2 and 4.3 ppbv for XCH4. The bias between the two data sets is 3.9 ppmv for XCO2 and 13.0 ppbv for XCH4. In order to avoid sensitivity-dependent artifacts, the EM27/SUN is also compared to a truncated IFS 125HR data set derived from full-resolution TCCON interferograms. The drift is 0.02 ppmv for XCO2 and 0.2 ppbv for XCH4 per year, with 1σ precisions of 0.4 ppmv for XCO2 and 1.4 ppbv for XCH4, respectively. The bias between the two data sets is 0.6 ppmv for XCO2 and 0.5 ppbv for XCH4. With the presented long-term stability, the EM27/SUN qualifies as an useful supplement to the existing TCCON network in remote areas. To achieve consistent performance, such an extension requires careful testing of any spectrometers involved by application of common quality assurance measures. One major aim of the COllaborative Carbon Column Observing Network (COCCON) infrastructure is to provide these services to all EM27/SUN operators. In the framework of COCCON development, the performance of an ensemble of 30 EM27/SUN spectrometers was tested and found to be very uniform, enhanced by the centralized inspection performed at the Karlsruhe Institute of Technology prior to deployment. Taking into account measured instrumental line shape parameters for each spectrometer, the resulting average bias across the ensemble with respect to the reference EM27/SUN used in the long-term study in XCO2 is 0.20 ppmv, while it is 0.8 ppbv for XCH4. The average standard deviation of the ensemble is 0.13 ppmv for XCO2 and 0.6 ppbv for XCH4. In addition to the robust metric based on absolute differences, we calculate the standard deviation among the empirical calibration factors. The resulting 2σ uncertainty is 0.6 ppmv for XCO2 and 2.2 ppbv for XCH4. As indicated by the executed long-term study on one device presented here, the remaining empirical calibration factor deduced for each individual instrument can be assumed constant over time. Therefore the application of these empirical factors is expected to further improve the EM27/SUN network conformity beyond the scatter among the empirical calibration factors reported above.

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A long-term study of Rattus norvegicus in the London Borough of Enfield using baiting returns as an indicator of sewer population levels

Epidemiology and Infection ◽

10.1017/s095026889900446x ◽

2000 ◽

Vol 125 (2) ◽

pp. 441-445 ◽

Cited By ~ 21

Author(s):

D. CHANNON ◽

M. COLE ◽

L. COLE

Keyword(s):

Rattus Norvegicus ◽

Decomposition Analysis ◽

Population Fluctuations ◽

Term Study ◽

Data Set ◽

Sewerage System ◽

Long Term Study ◽

Base Time ◽

Underlying Trend

This is a long-term study that investigates the dynamics of a population of Rattus norvegicus (Berk) inhabiting a sewerage system in London. Thirteen years (1986/7–1998/9) of data from sewer baiting records were analysed (a total of 35478 records). Manholes were baited with the anticoagulant Brodifacoum (0·005%) on a pinhead oatmeal bait base. Time series analysis was conducted on the data set to determine the underlying trend of the data and the population fluctuations about this trend. An exponential curve was found to give an accurate and realistic fit to the data and indicated that the rat population had decreased over the study period. Decomposition analysis indicated a 5-year cycle best described fluctuations around this trend.

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Between Food and Drugs

Revista Ingesta ◽

10.11606/issn.2596-3147.v1i2p73 ◽

2019 ◽

Vol 1 (2) ◽

pp. 73

Author(s):

Bruno Laurioux

Keyword(s):

Western Europe ◽

Unit Cost ◽

Far East ◽

17Th Century ◽

High Quality ◽

Term Study ◽

Ancient Medicine ◽

Long Term Study ◽

Travel Writings

From 1st to 17th centuries, spices have been a commodity as well as a necessity for the Western Europe. These “aromatic items of commerce with a high unit cost... imported from distant lands”, as they are defined by Paul Freedman, included many dry products that were mainly culinary ingredients, but also perfumes of high quality which could be used in cooking. Most of spices were supposed to have medical properties too: they were drugs, in the wide meaning that the Ancient Medicine gave to this term. The medical impacts of spices partly explain how, in 14th and 15th centuries, Far East spices offered the wider range of tastes and scents that European cuisine has ever known. But even when the French Cuisine has got rid of eastern spices from the middle of the 17th century, these ones remained quite important in a medicine that kept alive the principles of the Ancient Medicine. How the changing tastes affected the discourse on spices? We will answer this question through a long-term study of cook recipes, medical instructions and travel writings.

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