8,560 research outputs found
MgII absorption systems with W_0 > 0.1 \AA for a radio selected sample of 77 QSOs and their associated magnetic fields at high redshifts
We present a catalogue of MgII absorption systems obtained from high
resolution UVES/VLT data of 77 QSOs in the redshift range 0.6 < z < 2.0, and
down to an equivalent width W_0 > 0.1 \AA. The statistical properties of our
sample are found to be in agreement with those from previous work in the
literature. However, we point out that the previously observed increase with
redshift of dN/dz for weak absorbers, pertains exclusively to very weak
absorbers with W_0 < 0.1 \AA. Instead, dN/dz for absorbers with W_0 in the
range 0.1-0.3 \AA actually decreases with redshift, similarly to the case of
strong absorbers. We then use this catalogue to extend our earlier analysis of
the links between the Faraday Rotation Measure of the quasars and the presence
of intervening MgII absorbing systems in their spectra. In contrast to the case
with strong MgII absorption systems W_0 > 0.3 \AA, the weaker systems do not
contribute significantly to the observed Rotation Measure of the background
quasars. This is possibly due to the higher impact parameters of the weak
systems compared to strong ones, suggesting that the high column density
magnetized material that is responsible for the Faraday Rotation is located
within about 50 kpc of the galaxies. Finally, we show that this result also
rules out the possibility that some unexpected secondary correlation between
the quasar redshift and its intrinsic Rotation Measure is responsible for the
association of high Rotation Measure and strong intervening MgII absorption
that we have presented elsewhere, since this would have produced an equal
effect for the weak absorption line systems, which exhibit a very similar
distribution of quasar redshifts.Comment: Accepted for publication in ApJ. 12 pages, 8 figure
Why overlearned sequences are special: distinct neural networks in the right hemisphere for ordinal sequences
Written and spoken words activate left hemisphere areas involved in language processing. However, we here show that overlearned sequences (e.g. letters, numbers, weekdays, months) involve an unexpected right hemispheric activation in both the middle temporal gyrus and temporoparietal junction. Our findings offer a framework for understanding neuropsychological patterns seen in conditions such as synesthesia, in which anomalous perceptual experiences are triggered by overlearned sequences, and also in semantic dementia, in which left hemisphere damage disrupts word knowledge even while sequences can be spared
Thermal feedback in Si JFETs operating at low temperatures
Thermal feedback theory for silicon junction FET operating at low temperature
Predictability engenders more efficient neural responses
The neural response to a stimulus diminishes with repeated presentations, a phenomenon known as repetition suppression. We here use neuroimaging to demonstrate that repetition suppression appears to be a special case of "prediction suppression"--that is, the brain shows diminishing activity when subsequent stimuli in a train are predictable. This demonstration supports the hypothesis that the brain dynamically leverages prediction to minimize energy consumption
Measuring Sustainability
Planning for sustainability is high on many agendas, and tools to measure sustainability have been developed. Sustainable processes are those whose rates are maintained over time without exceeding the innate ability of its surroundings to support the process. We present the necessary conditions along with a new algorithm for measuring the sustainability of processes that integrates the laws of thermodynamics with laws for rate processes. The algorithm permits the assessment of the degree of sustainability of any process, whether ecological, economic, or social, as well as chemical or biological. It is a dynamic approach that applies at any scale and takes into consideration the spatial and temporal factors of processes, thus permitting empirical applications that correspond to real world (dynamic, complex, evolving) conditions across space and time. These characteristics make it especially suitable for applications in the field of spatial planning
Mashing up Visual Languages and Web Mash-ups
Research on web mashups and visual languages
share an interest in human-centered computing. Both
research communities are concerned with supporting
programming by everyday, technically inexpert users.
Visual programming environments have been a focus for
both communities, and we believe that there is much to
be gained by further discussion between these research
communities. In this paper we explore some connections
between web mashups and visual languages, and try to
identify what each might be able to learn from the other.
Our goal is to establish a framework for a dialog
between the communities, and to promote the exchange
of ideas and our respective understandings of humancentered
computing.published or submitted for publicationis peer reviewe
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