1,764 research outputs found
Mirage: a new iterative Map-Making code for CMB experiments
A major goal of CMB experiments is to obtain highly sensitive CMB maps in
order to extract Spherical Harmonic Power Spectrum (SHPS) and cosmological
parameters with unprecedented accuracy. We present a new map-making code
(Mirage), based on a two-phase iterative algorithm, involving low frequency
drift treatment, Butterworth high-pass filtering and conjugate gradient method.
This work was strongly motivated by Archeops CMB experiment data analysis. We
believe that Archeops was a good test bench for the future Planck Surveyor data
analysis, and Mirage was designed in order to be used for Planck data
processing with minimal work. A strong feature of Mirage is that it handles
experimental problems in data, such as holes in data stream, bright sources,
and galaxy side effects, without jeopardising speed. The other advantage is its
processing speed, allowing to run Monte Carlo simulations of Archeops data
processing on a single processor workstation overnight. Algorithms are
explained. Systematic effects on SHPS are investigated on various simulated
data, including typical Archeops observational systematics.
This code is available at adress http://www-dapnia.cea.fr/Telechargement/
Preprint with full resolution figures is available at
http://www-dapnia.cea.fr/Doc/Publications/Archives/dapnia-03-378.pdfComment: 11 pages, accepted in Astron. and Astrophysisc
Behavioral and neurobiological consequences of social subjugation during puberty in golden hamsters
In golden hamsters, offensive aggression is facilitated by vasopressin and inhibited by serotonin. We tested whether these neurotransmitter systems respond to modifications resulting from the stress of threat and attack (i.e., social subjugation) during puberty. Male golden hamsters were weaned at postnatal day 25 (P25), exposed daily to aggressive adults from P28 to P42, and tested for offensive aggression as young adults (P45). The results showed a context-dependent alteration in aggressive behavior. Subjugated animals were more likely to attack younger and weaker intruders than nonsubjugated controls. Conversely, subjugated animals were less likely to attack animals of similar size and age. After testing, the animals were killed, and their brains were collected to determine whether these behavioral changes are underlined by changes in the vasopressin and serotonin systems. Social subjugation resulted in a 50% decrease in vasopressin levels within the anterior hypothalamus, a site involved in the regulation of aggression. Furthermore, whereas the density of vasopressin-immunoreactive fibers within the area was not significantly altered in subjugated animals, the number of serotonin-immunoreactive varicosities within the anterior hypothalamus and lateral septum was 20% higher in subjugated animals than in their controls. These results establish puberty as a developmental period sensitive to environmental stressors. Furthermore, the results show that changes in the vasopressin and serotonin systems can correlate with behavioral alterations, supporting the role of these two neurotransmitters in the regulation of aggression
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