Rethinking the Model of Moving Cosmic Strings Producing Anisotropy in the Microwave Background

We re-analyze the issue of redshifts induced by a moving cosmic string by looking at moving sources and observers on a conical spacetime in a fully relativistic approach. By replacing the concept of a moving spacetime with the more clearly defined concept of moving sources and observers in the string spacetime, we show that there is no effect: the only redshift is a Doppler shift due to the motion of the source or observer.Comment: 11 pages, LaTex file, 1 figure available in PostScript format at ftp://manitou.astro.utoronto.ca/pub/string/ (get fig1_mdp.ps

Introductory programming: a systematic literature review

As computing becomes a mainstream discipline embedded in the school curriculum and acts as an enabler for an increasing range of academic disciplines in higher education, the literature on introductory programming is growing. Although there have been several reviews that focus on specific aspects of introductory programming, there has been no broad overview of the literature exploring recent trends across the breadth of introductory programming. This paper is the report of an ITiCSE working group that conducted a systematic review in order to gain an overview of the introductory programming literature. Partitioning the literature into papers addressing the student, teaching, the curriculum, and assessment, we explore trends, highlight advances in knowledge over the past 15 years, and indicate possible directions for future research

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Database of Variance Ratios of Nutrient Intakes from Publications and Reanalyzed Datasets

Ratios of within- and between-individual variation in nutrient intakes were compiled from publications or reports and from reanalyses of existing datasets. These ratios can potentially be used as external adjustment factors in analyses of nutrient intake data from studies that only collected one 24-hour dietary recall or food record per individual, in order to account for the proportion of total variance in nutrient intakes attributable to within-individual variation in population usual intake distributions. Careful consideration of the comparability of study characteristics and analytical approaches between the study from which a candidate external ratio is derived and study it will be used for is advised. See provided references for additional information on the original studies