77 research outputs found
Detection in coincidence of gravitational wave bursts with a network of interferometric detectors (I): Geometric acceptance and timing
Detecting gravitational wave bursts (characterised by short durations and
poorly modelled waveforms) requires to have coincidences between several
interferometric detectors in order to reject non-stationary noise events. As
the wave amplitude seen in a detector depends on its location with respect to
the source direction and as the signal to noise ratio of these bursts are
expected to be low, coincidences between antennas may not be so likely. This
paper investigates this question from a statistical point of view by using a
simple model of a network of detectors; it also estimates the timing precision
of a detection in an interferometer which is an important issue for the
reconstruction of the source location, based on time delays.Comment: low resolution figure 1 due to file size problem
The hippocampus as the switchboard between perception and memory.
Adaptive memory recall requires a rapid and flexible switch
from external perceptual reminders to internal mnemonic representations.
However, owing to the limited temporal or spatial
resolution of brain imaging modalities used in isolation, the
hippocampal–cortical dynamics supporting this process remain
unknown. We thus employed an object-scene cued recall paradigm
across two studies, including intracranial electroencephalography
(iEEG) and high-density scalp EEG. First, a sustained increase in hippocampal
high gamma power (55 to 110 Hz) emerged 500 ms after
cue onset and distinguished successful vs. unsuccessful recall. This
increase in gamma power for successful recall was followed by a
decrease in hippocampal alpha power (8 to 12 Hz). Intriguingly,
the hippocampal gamma power increase marked the moment at
which extrahippocampal activation patterns shifted from perceptual
cue toward mnemonic target representations. In parallel,
source-localized EEG alpha power revealed that the recall signal
progresses from hippocampus to posterior parietal cortex and
then to medial prefrontal cortex. Together, these results identify
the hippocampus as the switchboard between perception and
memory and elucidate the ensuing hippocampal–cortical dynamics
supporting the recall process.post-print1844 K
The E1A-Associated p400 Protein Modulates Cell Fate Decisions by the Regulation of ROS Homeostasis
The p400 E1A-associated protein, which mediates H2A.Z incorporation at specific promoters, plays a major role in cell fate decisions: it promotes cell cycle progression and inhibits induction of apoptosis or senescence. Here, we show that p400 expression is required for the correct control of ROS metabolism. Depletion of p400 indeed increases intracellular ROS levels and causes the appearance of DNA damage, indicating that p400 maintains oxidative stress below a threshold at which DNA damages occur. Suppression of the DNA damage response using a siRNA against ATM inhibits the effects of p400 on cell cycle progression, apoptosis, or senescence, demonstrating the importance of ATM–dependent DDR pathways in cell fates control by p400. Finally, we show that these effects of p400 are dependent on direct transcriptional regulation of specific promoters and may also involve a positive feedback loop between oxidative stress and DNA breaks since we found that persistent DNA breaks are sufficient to increase ROS levels. Altogether, our results uncover an unexpected link between p400 and ROS metabolism and allow deciphering the molecular mechanisms largely responsible for cell proliferation control by p400
The Virgo data acquisition system
International audienc
The gravitational wave detector VIRGO
International audienc
Gastrointestinal Hyperplasia with Altered Expression of DNA Polymerase β
Background: Altered expression of DNA polymerase β (Pol β) has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol β over-expression has not yet been evaluated in a mouse model. Methodology/Principal Findings: We have recently developed a novel transgenic mouse model that over-expresses Pol β. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol β over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol β expression. We observed elevated expression of Pol β in stomach adenomas and thyroid follicular carcinomas, but reduced Pol β expression in esophageal adenocarcinomas and squamous carcinomas. Conclusions/Significance: These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation
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