13 research outputs found
Milestones in the Observations of Cosmic Magnetic Fields
Magnetic fields are observed everywhere in the universe. In this review, we
concentrate on the observational aspects of the magnetic fields of Galactic and
extragalactic objects. Readers can follow the milestones in the observations of
cosmic magnetic fields obtained from the most important tracers of magnetic
fields, namely, the star-light polarization, the Zeeman effect, the rotation
measures (RMs, hereafter) of extragalactic radio sources, the pulsar RMs, radio
polarization observations, as well as the newly implemented sub-mm and mm
polarization capabilities.
(Another long paragraph is omitted due to the limited space here)Comment: Invited Review (ChJA&A); 32 pages. Sorry if your significant
contributions in this area were not mentioned. Published pdf & ps files (with
high quality figures) now availble at http://www.chjaa.org/2002_2_4.ht
Recovering the Inflationary Potential and Primordial Power Spectrum With a Slow Roll Prior: Methodology and Application to WMAP 3 Year Data
We introduce a new method for applying an inflationary prior to a
cosmological dataset that includes relations between observables at arbitrary
order in the slow roll expansion. The process is based on the inflationary flow
equations, and the slow roll parameters appear explicitly in the cosmological
parameter set. We contrast our method to other ways of imposing an inflationary
prior on a cosmological dataset, and argue that this method is ideal for use
with heterogeneous datasets. In particular, it would be well suited to
exploiting any direct detection of fundamental tensor modes by a BBO-style
mission. To demonstrate the practical use of this method we apply it to the
WMAPI+All dataset, and the newly released WMAPII dataset on its own and
together with the SDSS data. We find that all basic classes of single field
inflationary models are still allowed at the 1-2sigma level, but the overall
parameter space is sharply constrained. In particular, we find evidence that
the combination of WMAPII+SDSS is sensitive to effects arising from terms that
are quadratic in the two leading-order slow roll parameters.Comment: v2 adds references and fixes typos. New explanatory material added
clarifying effects that depend on terms that are second order in the slow
roll parameters, and the impact of the beam parametrization and SZ prior on
the central value of n_s v3: Added refs, minor clarifications, title
modified. In press with JCAP v4: New figures, with minor smoothing artifacts
removed. Matches published version. v5 Fixed typo in caption of Figure
Observations of the High Redshift Universe
(Abridged) In these lectures aimed for non-specialists, I review progress in
understanding how galaxies form and evolve. Both the star formation history and
assembly of stellar mass can be empirically traced from redshifts z~6 to the
present, but how the various distant populations inter-relate and how stellar
assembly is regulated by feedback and environmental processes remains unclear.
I also discuss how these studies are being extended to locate and characterize
the earlier sources beyond z~6. Did early star-forming galaxies contribute
significantly to the reionization process and over what period did this occur?
Neither theory nor observations are well-developed in this frontier topic but
the first results presented here provide important guidance on how we will use
more powerful future facilities.Comment: To appear in `First Light in Universe', Saas-Fee Advanced Course 36,
Swiss Soc. Astrophys. Astron. in press. 115 pages, 64 figures (see
http://www.astro.caltech.edu/~rse/saas-fee.pdf for hi-res figs.) For lecture
ppt files see
http://obswww.unige.ch/saas-fee/preannouncement/course_pres/overview_f.htm
Recommended from our members
Transient growth hormone deficiency after treatment of primary hypothyroidism
14-3-3 Proteins interact with the insulin-like growth factor receptor but not the insulin receptor1
Physical activity patterns and clusters in 1001 patients with COPD
We described physical activity measures and hourly patterns in patients with chronic obstructive pulmonary disease (COPD) after stratification for generic and COPD-specific characteristics and, based on multiple physical activity measures, we identified clusters of patients. In total, 1001 patients with COPD (65% men; age, 67 years; forced expiratory volume in the first second [FEV 1 ], 49% predicted) were studied cross-sectionally. Demographics, anthropometrics, lung function and clinical data were assessed. Daily physical activity measures and hourly patterns were analysed based on data from a multisensor armband. Principal component analysis (PCA) and cluster analysis were applied to physical activity measures to identify clusters. Age, body mass index (BMI), dyspnoea grade and ADO index (including age, dyspnoea and airflow obstruction) were associated with physical activity measures and hourly patterns. Five clusters were identified based on three PCA components, which accounted for 60% of variance of the data. Importantly, couch potatoes (i.e. the most inactive cluster) were characterised by higher BMI, lower FEV 1 , worse dyspnoea and higher ADO index compared to other clusters (p < 0.05 for all). Daily physical activity measures and hourly patterns are heterogeneous in COPD. Clusters of patients were identified solely based on physical activity data. These findings may be useful to develop interventions aiming to promote physical activity in COPD
A Space-based Observational Strategy for Characterizing the First Stars and Galaxies Using the Redshifted 21 cm Global Spectrum
New U–Pb Baddeleyite Ages of Mafic Dyke Swarms of the West African and Amazonian Cratons: Implication for Their Configuration in Supercontinents Through Time
International audienc