65 research outputs found
Detection of Bosenovae with Quantum Sensors on Earth and in Space
In a broad class of theories, the accumulation of ultralight dark matter
(ULDM) with particles of mass
leads the to formation of long-lived bound states known as boson stars. When
the ULDM exhibits self-interactions, prodigious bursts of energy carried by
relativistic bosons are released from collapsing boson stars in bosenova
explosions. We extensively explore the potential reach of terrestrial and
space-based experiments for detecting transient signatures of emitted
relativistic bursts of scalar particles, including ULDM coupled to photons,
electrons, and gluons, capturing a wide range of motivated theories. For the
scenario of relaxion ULDM, we demonstrate that upcoming experiments and
technology such as nuclear clocks as well as space-based interferometers will
be able to sensitively probe orders of magnitude in the ULDM coupling-mass
parameter space, challenging to study otherwise, by detecting signatures of
transient bosenova events. Our analysis can be readily extended to different
scenarios of relativistic scalar particle emission.Comment: 16 pages, 9 figure
Chromatin Structure Regulates Gene Conversion
Homology-directed repair is a powerful mechanism for maintaining and altering genomic structure. We asked how chromatin structure contributes to the use of homologous sequences as donors for repair using the chicken B cell line DT40 as a model. In DT40, immunoglobulin genes undergo regulated sequence diversification by gene conversion templated by pseudogene donors. We found that the immunoglobulin Vλ pseudogene array is characterized by histone modifications associated with active chromatin. We directly demonstrated the importance of chromatin structure for gene conversion, using a regulatable experimental system in which the heterochromatin protein HP1 (Drosophila melanogaster Su[var]205), expressed as a fusion to Escherichia coli lactose repressor, is tethered to polymerized lactose operators integrated within the pseudo-Vλ donor array. Tethered HP1 diminished histone acetylation within the pseudo-Vλ array, and altered the outcome of Vλ diversification, so that nontemplated mutations rather than templated mutations predominated. Thus, chromatin structure regulates homology-directed repair. These results suggest that histone modifications may contribute to maintaining genomic stability by preventing recombination between repetitive sequences
Regulation of activation-induced deaminase stability and antibody gene diversification by Hsp90
Hsp90 stabilizes and prevents degradation of cytoplasmic activation-induced deaminase
Genetic Variation Stimulated by Epigenetic Modification
Homologous recombination is essential for maintaining genomic integrity. A common repair mechanism, it uses a homologous or homeologous donor as a template for repair of a damaged target gene. Such repair must be regulated, both to identify appropriate donors for repair, and to avoid excess or inappropriate recombination. We show that modifications of donor chromatin structure can promote homology-directed repair. These experiments demonstrate that either the activator VP16 or the histone chaperone, HIRA, accelerated gene conversion approximately 10-fold when tethered within the donor array for Ig gene conversion in the chicken B cell line DT40. VP16 greatly increased levels of acetylated histones H3 and H4, while tethered HIRA did not affect histone acetylation, but caused an increase in local nucleosome density and levels of histone H3.3. Thus, epigenetic modification can stimulate genetic variation. The evidence that distinct activating modifications can promote similar functional outcomes suggests that a variety of chromatin changes may regulate homologous recombination, and that disregulation of epigenetic marks may have deleterious genetic consequences
Nanoparticulate Impurities in Pharmaceutical-Grade Sugars and their Interference with Light Scattering-Based Analysis of Protein Formulations
First neutrino interaction candidates at the LHC
FASER at the CERN Large Hadron Collider (LHC) is designed to directly
detect collider neutrinos for the first time and study their cross sections at
TeV energies, where no such measurements currently exist. In 2018, a pilot
detector employing emulsion films was installed in the far-forward region of
ATLAS, 480 m from the interaction point, and collected 12.2 fb of
proton-proton collision data at a center-of-mass energy of 13 TeV. We describe
the analysis of this pilot run data and the observation of the first neutrino
interaction candidates at the LHC. This milestone paves the way for high-energy
neutrino measurements at current and future colliders.Comment: Auxiliary materials are available at
https://faser.web.cern.ch/fasernu-first-neutrino-interaction-candidate
Late-Time Phase Transitions and Scalar Field Interactions with the Cosmic Neutrino Background
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