11,015 research outputs found
SNS Timing System
This poster describes the timing system being designed for Spallation Neutron
Source being built at Oak Ridge National lab
USF binding sequences from the HS4 insulator element impose early replication timing on a vertebrate replicator
The nuclear genomes of vertebrates show a highly organized program of DNA replication where GC-rich isochores are replicated early in S-phase, while AT-rich isochores are late replicating. GC-rich regions are gene dense and are enriched for active transcription, suggesting a connection between gene regulation and replication timing. Insulator elements can organize independent domains of gene transcription and are suitable candidates for being key regulators of replication timing. We have tested the impact of inserting a strong replication origin flanked by the β-globin HS4 insulator on the replication timing of naturally late replicating regions in two different avian cell types, DT40 (lymphoid) and 6C2 (erythroid). We find that the HS4 insulator has the capacity to impose a shift to earlier replication. This shift requires the presence of HS4 on both sides of the replication origin and results in an advance of replication timing of the target locus from the second half of S-phase to the first half when a transcribed gene is positioned nearby. Moreover, we find that the USF transcription factor binding site is the key cis-element inside the HS4 insulator that controls replication timing. Taken together, our data identify a combination of cis-elements that might constitute the basic unit of multi-replicon megabase-sized early domains of DNA replication
Dynamical model of sequential spatial memory: winnerless competition of patterns
We introduce a new biologically-motivated model of sequential spatial memory
which is based on the principle of winnerless competition (WLC). We implement
this mechanism in a two-layer neural network structure and present the learning
dynamics which leads to the formation of a WLC network. After learning, the
system is capable of associative retrieval of pre-recorded sequences of spatial
patterns.Comment: 4 pages, submitted to PR
The OscSNS White Paper
There exists a need to address and resolve the growing evidence for
short-baseline neutrino oscillations and the possible existence of sterile
neutrinos. Such non-standard particles require a mass of eV/c, far
above the mass scale associated with active neutrinos, and were first invoked
to explain the LSND appearance signal.
More recently, the MiniBooNE experiment has reported a excess of
events in antineutrino mode consistent with neutrino oscillations and with the
LSND antineutrino appearance signal. MiniBooNE also observed a
excess of events in their neutrino mode data. Lower than expected
neutrino-induced event rates using calibrated radioactive sources and nuclear
reactors can also be explained by the existence of sterile neutrinos. Fits to
the world's neutrino and antineutrino data are consistent with sterile
neutrinos at this eV/c mass scale, although there is some tension
between measurements from disappearance and appearance experiments. In addition
to resolving this potential major extension of the Standard Model, the
existence of sterile neutrinos will impact design and planning for all future
neutrino experiments. It should be an extremely high priority to conclusively
establish if such unexpected light sterile neutrinos exist. The Spallation
Neutron Source (SNS) at Oak Ridge National Laboratory, built to usher in a new
era in neutron research, provides a unique opportunity for US science to
perform a definitive world-class search for sterile neutrinos.Comment: This white paper is submitted as part of the SNOWMASS planning
proces
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