35,407 research outputs found
Fearless: Ally Siegel
Encouraging and mentoring young minds, consistently finding new ways to use her love of climbing and adventure to promote character and leadership development, and always ready for the next big challenge, Ally Siegel ’16 fearlessly pushes herself to achieve more, inspiring others to do the same. [excerpt
GW170817the first observed neutron star merger and its kilonova: implications for the astrophysical site of the r-process
The first neutron star (NS) merger observed by advanced LIGO and Virgo,
GW170817, and its fireworks of electromagnetic counterparts across the entire
electromagnetic spectrum marked the beginning of multi-messenger astronomy and
astrophysics with gravitational waves. The ultraviolet, optical, and
near-infrared emission was consistent with being powered by the radioactive
decay of nuclei synthesized in the merger ejecta by the rapid neutron capture
process (r-process). Starting from an outline of the inferred properties of
this 'kilonova' emission, I discuss possible astrophysical sites for r-process
nucleosynthesis in NS mergers, arguing that the heaviest r-process elements
synthesized in this event most likely originated in outflows from a post-merger
accretion disk. I compare the inferred properties of r-process element
production in GW170817 to current observational constraints on galactic heavy
r-process nucleosynthesis and discuss challenges merger-only models face in
explaining the r-process content of our galaxy. Based on the observational
properties of GW170817 and recent theoretical progress on r-process
nucleosynthesis in collapsars, I then show how GW170817 points to collapsars as
the dominant source of r-process enrichment in the Milky Way. These rare
core-collapse events arguably better satisfy existing constraints and overcome
problems related to r-process enrichment in various environments that NS
mergers face. Finally, I comment on the universality of the r-process and on
how variations in light r-process elements can be obtained both in NS mergers
and collapsars.Comment: 16 pages, 8 figures. Invited contribution to the EPJA Topical Issue
"First joint gravitational wave and electromagnetic observations:
Implications for nuclear and particle physics
Newburgh, Town of and CSEA, Town of Newburgh Unit, Orange County Local 836
In the Matter of the Fact-Finding between The Town of Newburgh, Public Employer, and The Civil Service Employees Association, Town of Newburgh Unit, Orange County Local 836, Employee Organization. Case No. M2005-177. BEFORE: Jay M. Siegel, Esq., Impartial Fact Finde
West Hempstead Union Free School District and West Hempstead Education Association
In the matter of the fact-finding between the West Hempstead Education Association, employer, and the West Hempstead Education Association, union. PERB case no. M2009-352. Before: Jay M. Siegel, Esq., fact finder
The performance and capabilities of terrestial organisms in extreme and unusual gaseous and liquid environments
Inhibitor effects of psilotin, MnO2, and D2O on substances existing in nature to determine performance of terrestrial organisms in extreme and unusual gaseous and liquid environment
Role of gravitational stress in land plant evolution - The gravitational factor in lignification Semiannual report
Gravitational effects on lignification in plant
Magnetic field amplification in hypermassive neutron stars via the magnetorotational instability
Mergers of binary neutron stars likely lead to the formation of a
hypermassive neutron star (HMNS), which is metastable and eventually collapses
to a black hole. This merger scenario is thought to explain the phenomenology
of short gamma-ray bursts (SGRBs). The very high energies observed in SGRBs
have been suggested to stem from neutrino-antineutrino annihilation and/or from
very strong magnetic fields created during or after the merger by mechanisms
like the magnetorotational instability (MRI). Here, we report on results that
show for the first time the development of the MRI in HMNSs in
three-dimensional, fully general-relativistic magnetohydrodynamic simulations.
This instability amplifies magnetic fields exponentially and could be a vital
ingredient in solving the SGRB puzzle.Comment: 6 pages, 3 figures. Proceedings of the Karl Schwarzschild Meeting
201
An upper bound from helioseismology on the stochastic background of gravitational waves
The universe is expected to be permeated by a stochastic background of
gravitational radiation of astrophysical and cosmological origin. This
background is capable of exciting oscillations in solar-like stars. Here we
show that solar-like oscillators can be employed as giant hydrodynamical
detectors for such a background in the muHz to mHz frequency range, which has
remained essentially unexplored until today. We demonstrate this approach by
using high-precision radial velocity data for the Sun to constrain the
normalized energy density of the stochastic gravitational-wave background
around 0.11 mHz. These results open up the possibility for asteroseismic
missions like CoRoT and Kepler to probe fundamental physics.Comment: 6 pages, 2 figures. Updated to match published versio
Implementing the syntax of japanese numeral classifiers
While the sortal constraints associated with Japanese numeral classifiers are wellstudied, less attention has been paid to the details of their syntax. We describe an analysis implemented within a broadcoverage HPSG that handles an intricate set of numeral classifier construction types and compositionally relates each to an appropriate semantic representation, using Minimal Recursion Semantics
- …