Structure in gamma ray burst time profiles: Statistical Analysis 1

Since its launch on April 5, 1991, the Burst And Transient Source Experiment (BATSE) has observed and recorded over 500 gamma-ray bursts (GRB). The analysis of the time profiles of these bursts has proven to be difficult. Attempts to find periodicities through Fourier analysis have been fruitless except one celebrated case. Our goal is to be able to qualify the observed time-profiles structure. Before applying this formation to bursts, we have tested it on profiles composed of random Poissonian noise. This paper is a report of those preliminary results

Effective depth of spectral line formation in planetary atmospheres

The effective level of line formation for spectroscopic absorption lines has long been regarded as a useful parameter for determining average atmospheric values of the quantities involved in line formation. The identity of this parameter was recently disputed. The dependence of this parameter on the average depth where photons are absorbed in a semi-infinite atmosphere is established. It is shown that the mean depths derived by others are similar in nature and behavior

Microplastic Abundance, Distribution and Impacts on Sargassum-Associated Juvenile Fishes in the Gulf of Mexico

Microplastics are a concern in marine environments because they are highly durable, ubiquitous, and can be mistaken for food and ingested by small organisms. Pelagic Sargassum, an important habitat for larval and juvenile stages of many fish species, is found in large surface aggregations, and may provide complex structure in which microplastics become trapped. This could lead to greater risk of microplastic ingestion by fish early life stages associated with Sargassum habitats. To better understand the impacts of microplastics within Sargassum communities, this study examined 1) microplastic concentrations and ingestion by juvenile fishes associated with Sargassum; 2) the microbial communities associated with the Sargassum and microplastics; and 3) the influence of microplastic ingestion on the microbiomes of juvenile Gray Triggerfish. Neuston net samples were collected in 2017 and 2018 from open water and Sargassum habitats in the Gulf of Mexico to collect microplastics and fishes. Microplastic abundance was significantly higher in Sargassum habitats relative to open water habitats. Microplastics were identified in the stomach contents of many species of juvenile fishes with total microplastic frequency of occurrence ranging between 14.7-24.7%. Microplastics had a unique microbiome when compared to the surrounding environment. The microplastic microbiome was found to influence Gray Triggerfish gut microbiomes. The results from this project demonstrate that microplastics are being ingested by juvenile fishes in Sargassum and the unique microbiome of microplastics are influencing fish gut microbiomes

VLBI for Gravity Probe B. V. Proper Motion and Parallax of the Guide Star, IM Pegasi

We present the principal astrometric results of the very-long-baseline interferometry (VLBI) program undertaken in support of the Gravity Probe B (GP-B) relativity mission. VLBI observations of the GP-B guide star, the RS CVn binary IM Pegasi (HR 8703), yielded positions at 35 epochs between 1997 and 2005. We discuss the statistical assumptions behind these results and our methods for estimating the systematic errors. We find the proper motion of IM Peg in an extragalactic reference frame closely related to the International Celestial Reference Frame 2 (ICRF2) to be -20.83 +- 0.03 +- 0.09 mas/yr in right ascension and -27.27 +- 0.03 +- 0.09 mas/yr in declination. For each component the first uncertainty is the statistical standard error and the second is the total standard error (SE) including plausible systematic errors. We also obtain a parallax of 10.37 +- 0.07 mas (distance: 96.4 +- 0.7 pc), for which there is no evidence of any significant contribution of systematic error. Our parameter estimates for the ~25-day-period orbital motion of the stellar radio emission have SEs corresponding to ~0.10 mas on the sky in each coordinate. The total SE of our estimate of IM Peg's proper motion is ~30% smaller than the accuracy goal set by the GP-B project before launch: 0.14 mas/yr for each coordinate of IM Peg's proper motion. Our results ensure that the uncertainty in IM Peg's proper motion makes only a very small contribution to the uncertainty of the GP-B relativity tests.Comment: Accepted for publication in the Astrophysical Journal Supplement Serie

Dimensional metrology and positioning operations: basics for a spatial layout analysis of measurement systems

Dimensional metrology and positioning operations are used in many fields of particle accelerator projects. This lecture gives the basic tools to designers in the field of measure by analysing the spatial layout of measurement systems since it is central to dimensional metrology as well as positioning operations. In a second part, a case study dedicated to a synchrotron storage ring is proposed from the detection of the magnetic centre of quadrupoles to the orbit definition of the ring.Comment: 60 pages, presented at the CERN Accelerator School CAS 2009: Specialised Course on Magnets, Bruges, 16-25 June 200

Die arbeitsmarktpolitischen Initiativen in Frankreich seit dem Regierungswechsel 1997 (The labour market policy initiatives in France since the change in government in 1997)

"Since the change in government in 1997 the socialist-orientated majority in France has been pursuing a new labour market policy which is based to a large extent on measures promised du-ring the election campaign. The interventions of the French state in industrial relations affect many areas which are regulated in other European countries by means of contracts between the two sides of industry. This report selects two particularly current areas, these are the introduc-tion of the 35-hour working week and the subsidisation of certain employment profiles, in par-ticular the arrangement of jobs for young unemployed people. The French government, which favours the redistribution of labour more than deregulation in order to combat unemployment, is reducing the statutory working week for companies with more than 20 employees to 35 hours a week as from January 2000. This measure, which is accompanied by substantial financial support, is regarded as an essential stimulus to promote negotiations at industry or company level. Although the attitude of the public and the two sides of industry towards the 35-hour working week is somewhere between hesitant and negative, the job creation measures for problem groups, in particular the creation of 35,000 jobs for young jobseekers in the public service is regarded more with approval, as French society sees it as the task of the state to protect its weaker members." (Author's abstract, IAB-Doku) ((en))Arbeitsmarktpolitik, Arbeitszeitverkürzung, Arbeitslosigkeitsbekämpfung, arbeitslose Jugendliche, Frankreich

Astrometric accuracy of phase-referenced observations with the VLBA and EVN

Astrometric accuracy of complex modern VLBI arrays cannot be calculated analytically. We study the astrometric accuracy of phase-referenced VLBI observations for the VLBA, EVN and global VLBI array by simulating VLBI data for targets at declinations -25$^\circ$, 0$^\circ$, 25$^\circ$, 50$^\circ$, 75$^\circ$ and 85$^\circ$. The systematic error components considered in this study are calibrator position, station coordinate, Earth orientation and troposphere parameter uncertainties. We provide complete tables of the astrometric accuracies of these arrays for a source separation of 1$^\circ$ either along the right ascension axis or along the declination axis. Astrometric accuracy is 50microas at mid declination and is 300microas at low (-25$^\circ$) and high (85$^\circ$) declinations for the VLBA and EVN. In extending our simulations to source separations of 0.5$^\circ$ and 2$^\circ$, we establish the formula for the astrometric accuracy of the VLBA: Delta = (Delta_1$^\circ$-14)*d+ 14 (microas) where Delta_1$^\circ$ is the astrometric accuracy for a separation d=1$^\circ$ provided in our tables for various declinations and conditions of the wet troposphere. We argue that this formula is also valid for the astrometric accuracy of the EVN and global VLBI array.Comment: 10 pages, 4 figures, accepted for publication in Journal of Astrophysics and Astronom

LES RESSOURCES HUMAINES ET LA STRATEGIE DE L’ENTRPRISE

HUMAN RESOURCES AND COMPANY STRATEGY This article focuses on the issue of HUMAN RESOURCES AND CORPORATE STRATEGY from a strategic point of view and Globalization and its impact on Human resources