2,460 research outputs found
An automated atmospheric sampling system operating on 747 airliners
An air sampling system that automatically measures the temporal and spatial distribution of selected particulate and gaseous constituents of the atmosphere has been installed on a number of commercial airliners and is collecting data on commercial air routes covering the world. Measurements of constituents related to aircraft engine emissions and other pollutants are made in the upper troposphere and lower stratosphere (6 to 12 km) in support of the Global Air Sampling Program (GASP). Aircraft operated by different airlines sample air at latitudes from the Arctic to Australia. This system includes specialized instrumentation for measuring carbon monoxide, ozone, water vapor, and particulates, a special air inlet probe for sampling outside air, a computerized automatic control, and a data acquisition system. Air constituents and related flight data are tape recorded in flight for later computer processing on the ground
Characterisation of the Repeat Breeding Syndrome in Swedish Dairy Cattle
Repeat breeding (RB), defined as cows failure to conceive from 3 or more regularly spaced services in the absence of detectable abnormalities, is a costly problem for the dairy producer. To elucidate the occurrence of RB in Swedish dairy herds and to identify risk factors of the syndrome totally 57,616 dairy cows in 1,541 herds were investigated based on data from the official Swedish production-, AI- and disease- recording schemes. The characteristics of the RB syndrome were studied on both herd and individual cow level. The effects of risk factors on the herd frequency of RB were studied by logistic regression. A generalised linear mixed model with logit link, and accounting for herd-level variation by including a random effect of herd, was used to study the individual animal risk for RB. The total percentage of RB animals was 10.1% and the median proportion of RB animals in the herds studied was 7.5%. The proportion of RB cows in herds increased with decreased herd sizes with decreased average days from calving to first AI, with increased herd incidence of clinical mastitis, with decreased reproductive disorders, and increased other diseases treated by a veterinarian. On animal level, the risk factors were milk yield, lactation number, difficult calving or dystocia, season at first service, days in milk at first service and veterinary treatment for reproductive disorders before the first service. Cows being an RB animal in the previous lactation had a higher risk of becoming an RB animal also in the present lactation. In conclusion our results show that the repeat breeding syndrome is a multifactorial problem involving a number of extrinsic factors as well as intrinsic factors coupled to the individual animal
An automated system for global atmospheric sampling using B-747 airliners
The global air sampling program utilizes commercial aircrafts in scheduled service to measure atmospheric constituents. A fully automated system designed for the 747 aircraft is described. Airline operational constraints and data and control subsystems are treated. The overall program management, system monitoring, and data retrieval from four aircraft in global service is described
Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
Large Galactic stellar surveys and new generations of stellar atmosphere
models and spectral line formation computations need to be subjected to careful
calibration and validation and to benchmark tests. We focus on cool stars and
aim at establishing a sample of 34 Gaia FGK Benchmark Stars with a range of
different metallicities. The goal was to determine the effective temperature
and the surface gravity independently from spectroscopy and atmospheric models
as far as possible. Fundamental determinations of Teff and logg were obtained
in a systematic way from a compilation of angular diameter measurements and
bolometric fluxes, and from a homogeneous mass determination based on stellar
evolution models. The derived parameters were compared to recent spectroscopic
and photometric determinations and to gravity estimates based on seismic data.
Most of the adopted diameter measurements have formal uncertainties around 1%,
which translate into uncertainties in effective temperature of 0.5%. The
measurements of bolometric flux seem to be accurate to 5% or better, which
contributes about 1% or less to the uncertainties in effective temperature. The
comparisons of parameter determinations with the literature show in general
good agreements with a few exceptions, most notably for the coolest stars and
for metal-poor stars. The sample consists of 29 FGK-type stars and 5 M giants.
Among the FGK stars, 21 have reliable parameters suitable for testing,
validation, or calibration purposes. For four stars, future adjustments of the
fundamental Teff are required, and for five stars the logg determination needs
to be improved. Future extensions of the sample of Gaia FGK Benchmark Stars are
required to fill gaps in parameter space, and we include a list of suggested
candidates.Comment: Accepted by A&A; 34 pages (printer format), 14 tables, 13 figures;
language correcte
Frequency-modulation spectroscopy with blue diode lasers
Frequency-modulation spectroscopy provides ultrasensitive absorption measurements. The technique is especially adaptable to diode lasers, which can be modulated easily, and has been used extensively in the near-infrared and infrared spectral regions. The availability of blue diode lasers now means that the accessible wavelength region can be increased. We successfully demonstrate wavelength-modulation spectroscopy and two-tone frequency-modulation spectroscopy for the weak second resonance line of potassium at 404.8 nm and for the transition at 405.8 nm in lead, starting from the thermally populated 6p(2) P-3(2) metastable level, information on the modulation parameters is obtained with a fitting procedure. Experimental signal-to-noise ratios: at different absorption levels are compared with theoretical signal-to-noise ratios and show good agreement. Detection sensitivities of 2 x 10(-6) and 5 x 10(-6) for wavelength and two-tone frequency-modulation spectroscopy, respectively, for a 120-Hz bandwidth are demonstrated. (C) 2000 Optical Society of America
The Swedish Housing Market: Structure, Policy Issues and Modeling
Contribution to the Metropolitan Study: 20 -- The project "Nested Dynamics of Metropolitan Processes and Policies" is a collaborative study within the project area Regional Issues at IIASA. The series of contributions is a means of conveying information between the collaborators in the network of the project.
This paper reports on a penetrating investigation of the housing market in the Stockholm region. It is based on a sequence of interviews and discussions with various decision makers and managers whose actions form an important market system. The paper examines the details of the system structure with the objective of formulating a reliable model of transactions, regulations, investments, etc. The work on the model itself is currently underway and will also be presented in the near future.
The approach undertaken by the authors is original in its careful treatment of such system properties which constitute deviations from a free market. Consequently, the paper provides an already tested guideline for the work on the housing sector in other metropolitan regions in the study. Recently, this type of work has been initiated in several of those regions. It is believed that this work may bring about a new generation of housing sector modeling and a renewal of the pertinent analyses
Operasjonalisering av beredskapslitteraturen i en norsk kontekst
Oppgaven forsøker å forklare norsk politikk for beredskap i lys av et sentralt paradigme innenfor fagfeltet. Problemstillingen min er: I hvilken grad er de sentrale modellene i beredskapslitteraturen operasjonalisert i norsk beredskap og krisehåndtering? I tillegg til problemstillingen, har jeg formulert to forskningsspørsmål: Kan beredskapslitteraturen som ligger til grunn i beredskapsplanene, sees igjen i praksis i lys av Koronapandemien? Eksisterer det et behov for oppdatering av beredskapsplanene? Oppgaven forsøker, gjennom intervju av informanter og ved hjelp av sentral forskningslitteratur, å besvare denne problemstillingen. I 2018 la direktoratet for samfunnssikkerhet og beredskap frem en erstatning for Veiledning til forskrift om kommunal beredskapsplikt av 2012. Veilederen skal bidra til en felles forståelse av kravene til kommunal beredskapsplikt, slik at alle har likt utgangspunkt. Beredskapsplaner er i hyppig utvikling, og gjenspeiler hvordan de ulike nasjonale samfunnssikkerhetsperspektivene organiseres. Hvordan den norske beredskapen er organisert og gjenspeiles i beredskapsplanene, er utgangspunktet for oppgaven. Dette vil kobles opp mot kommunal praksis, gjennom håndtering av Koronapandemien
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