Commutators on ℓ1\ell_1

The main result is that the commutators on $\ell_1$ are the operators not of the form $\lambda I + K$ with $\lambda\neq 0$ and $K$ compact. We generalize Apostol's technique (1972, Rev. Roum. Math. Appl. 17, 1513 - 1534) to obtain this result and use this generalization to obtain partial results about the commutators on spaces \X which can be represented as \displaystyle \X\simeq (\bigoplus_{i=0}^{\infty} \X)_{p} for some $1\leq p<\infty$ or $p=0$. In particular, it is shown that every compact operator on $L_1$ is a commutator. A characterization of the commutators on $\ell_{p_1}\oplus\ell_{p_2}\oplus...\oplus\ell_{p_n}$ is given. We also show that strictly singular operators on $\ell_{\infty}$ are commutators.Comment: 17 pages. Submitted to the Journal of Functional Analysi

Arkansas Animal Science Department Report 2002

The faculty and staff of the Animal Science Program are pleased to present the sixth edition of the Arkansas Animal Science Report. As with virtually all programs in the country, budget constraints presented serious challenges to teaching, research, and extension programming. However, the faculty and staff responded with innovation, good management, and hard work to maintain a productive program designed to benefit the students of the University and the citizens of the state. We are committed to remaining faithful to our Land-Grant mission. A sincere thank you is owed to Dr. Zelpha Johnson and Dr. Wayne Kellogg for editing this publication. We are proud that Meat and Poultry magazine ranked the animal and poultry programs at the University of Arkansas among the top four in the United States for 2003. This is a tribute to the dedicated and talented faculty in the Departments of Animal Science, Poultry Science, and Food Science and to their high level of cooperation

Companions of Qsos at Redshift 1.1

We discuss broad- and narrow-band imaging of 7 arcmin fields of 14 QSOs with redshift ~1.1. The narrow-band filters were chosen to detect redshifted [O II] 3727A, and the broad bands are R and I, which correspond to rest wavelengths {}~3300A and ~3800A. In 100 arcsec subfields surrounding the QSOs, we detect an excess of typically 15 detected objects over the background of 25. Several of the QSO subfields also contain an excess of blue (R-I < 1.0) galaxies compared with the other subfields. Finally, several of the QSO subfields contain an excess of galaxies with significant narrow-band flux compared with the other subfields, and many of these are also blue. Most of the QSOs are radio-quiet in a region of sky overpopulated with z=1.1 QSOs, and 3 others are radio-loud from other parts of the sky. We suggest that most of these z=1.1 QSOs are in compact groups of starbursting galaxies. In our data, there is no significant difference between radio-loud and radio-quiet QSOs. We discuss cosmic evolutionary implications.Comment: 9 pages Plain Tex, 8 figures upon request, SISSA-DAO-94-00

Sampling design for compliance monitoring of surface water quality: A case study in a Polder area

International agreements such as the EU Water Framework Directive (WFD) ask for efficient sampling methods for monitoring natural resources. In this paper a general methodology for designing efficient, statistically sound monitoring schemes is described. An important decision is the choice between a design-based and a model-based method, implying the choice between probability (random) sampling and purposive sampling. For mapping purposes, model-based methods are more appropriate, whereas to obtain valid results for the universe as a whole, such as in testing water quality standards against legal standards, we generally prefer a design-based method. Four basic sampling patterns in space-time universe are described: static, synchronous, static-synchronous, and rotational. A case study is carried out for monitoring the quality of surface water at two farms in western Netherlands, wherein a synchronous sampling design is applied, with stratified simple random sampling in both space and time. To reduce laboratory costs the aliquots taken at the locations of a given sampling round are bulked to form a composite. To test the spatiotemporal mean N-total concentration during the summer half-year against the MAR standard with a power of 80% at a concentration 15% below the MAR standard and with a confidence of 95%, six to nine sampling rounds are needed with 50 to 75 locations per sampling round. For P-total the required number of sampling rounds differs strongly between the two farms, but is for both farms much larger than for N-total

Development of a Space Vehicle Electromagnetic Interference/compatibility Specification. Volume 3 - System Specification

This specification represents a new approach to controlling electromagnetic interference. In this approach the system integration contractor will be responsible for the development of discrete specification limits to be utilized on the program to which this specification is applied. The specification limits imposed upon subsystem contractors will be developed by the use of a computer program, available from the procuring agency, which is designed to consider the total system electromagnetic environment in the computation of these limits. The integration contractor will be required to mathematically model those circuits which represent required emitters and receptors of electromagnetic energy on the space vehicle. There are contained herein, a list of available computer models into which must be inserted particular parameters of the spacecraft subsystems. These functional models, when inserted into the computer program, will develop discrete specification limits based upon the requirements of the particular system modelled