2,464 research outputs found
Goodbye Copenhagen
A deeper look at the Lorentz force causes quantum superposition to vanish into thin air. Fully understanding this 1895 Lorentz force, will help us all finally say Goodbye to the Copenhagen Interpretation of quantum physics. This powerful Lorentz force fully penetrates all atomic orbitals, all atomic nuclei, and all the inner structures of all the subatomic particles. There is no need for the bewildering 96-year-old Copenhagen Interpretation, because we are now able to look very closely at the Lorentz force of 1895. This Goodbye Copenhagen article of 2023, explains how this mighty Lorentz force, completely destroys the old Copenhagen Interpretation of quantum mechanics. These old Self-Contradictory Interpretations are no longer needed today in 2023; because now we are finally able to inspect the 1895 Lorentz force more deeply.71 pages of size 14 fon
Road Dust Lead (Pb) in Two Neighborhoods of Urban Atlanta, (GA, USA)
Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust (\u3c250 \u3eμm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution
Adiabatic approximation with exponential accuracy for many-body systems and quantum computation
We derive a version of the adiabatic theorem that is especially suited for
applications in adiabatic quantum computation, where it is reasonable to assume
that the adiabatic interpolation between the initial and final Hamiltonians is
controllable. Assuming that the Hamiltonian is analytic in a finite strip
around the real time axis, that some number of its time-derivatives vanish at
the initial and final times, and that the target adiabatic eigenstate is
non-degenerate and separated by a gap from the rest of the spectrum, we show
that one can obtain an error between the final adiabatic eigenstate and the
actual time-evolved state which is exponentially small in the evolution time,
where this time itself scales as the square of the norm of the time-derivative
of the Hamiltonian, divided by the cube of the minimal gap.Comment: 22 pages, 2 figures. Supersedes arXiv:0804.0604. v2: some
corrections, new remarks, and a new subsection on the adiabatic theorem for
open systems. v3: additional correction
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Dielectronic recombination for boronlike ions
We have calculated the total dielectronic recombination (DR) coefficients for the 2P1/2 and 2P3/2 states in B-like Ti17+, Fe21+, and Mo37+ ions for electron temperatures 0.1<~T<~10000 eV. The calculations are carried out using the multiconfiguration Dirac-Fock method in intermediate coupling with a configuration interaction. We find that accurate Coster-Kronig energies are critical for a successful determination of low-temperature DR coefficients. We also find that the DR involving fine-structure excitations can be as important as the 2s-2p excitation channels in the low-temperature regime for some ions
Bridging the Gap: Categorizing Gravitational-Wave Events at the Transition Between Neutron Stars and Black Holes
We search for features in the mass distribution of detected compact binary
coalescences which signify the transition between neutron stars and black
holes. We analyze all gravitational wave detections by LIGO-Virgo-KAGRA made
through the end of the first half of the third observing run, and find clear
evidence for two different populations of compact objects based solely on
gravitational wave data. We confidently (99.3%) find a steepening relative to a
single power law describing neutron stars and low-mass black holes below
, which is consistent with many predictions
for the maximum neutron star mass. We find suggestions of the purported lower
mass gap between the most massive neutron stars and the least massive black
holes, but are unable to conclusively resolve it with current data. If it
exists, we find the lower mass gap's edges to lie at and . We re-examine events that
have been deemed "exceptional" by the LIGO-Virgo-KAGRA collaborations in the
context of these features. We analyze GW190814 self-consistently in the context
of the full population of compact binaries, finding support for its secondary
to be either a neutron star or a lower mass gap object, consistent with
previous claims. Our models are the first to accommodate this event, which is
an outlier with respect to the binary black hole population. We find that
GW200105 and GW200115 probe the edges of, and may have components within, the
lower mass gap. As future data improve global population models, the
classification of these events will also improve
High-Velocity Estimates and Inverse Scattering for Quantum N-Body Systems with Stark Effect
In an N-body quantum system with a constant electric field, by inverse
scattering, we uniquely reconstruct pair potentials, belonging to the optimal
class of short-range potentials and long-range potentials, from the
high-velocity limit of the Dollard scattering operator. We give a
reconstruction formula with an error term.Comment: In this published version we have added remarks and we have edited
the pape
On the role of boron on improving ductility in a new polycrystalline superalloy
AbstractThe role of boron in promoting ductility at high temperature in a prototype nickel-based superalloy designed for industrial gas turbines is studied. Both a boron-containing and boron-free variant are tested in tension at 750 °C, with further in-situ tests carried out using scanning electron microscopy (SEM), to clarify the mechanism of ductility improvement. The improvement in ductility is observed to be greater at the lowest investigated strain rate, where the grain boundary character plays a significant role on the mechanical properties; no ductility improvement was observed at the highest investigated strain rate. The in-situ tests were also performed at 750 °C and revealed directly the greater susceptibility of the grain boundary morphology in the boron-free case to fracture and – in the boron-containing case – the mechanism of ductility enhancement. The findings are supported further by high-resolution electron backscattered diffraction (HR-EBSD) strain mapping which confirms that the distribution of elastic strain and geometrically necessary dislocation (GND) content are influenced markedly by boron addition. The mechanism through which boron indirectly enhances the mechanical properties at elevated temperatures is discussed
Faint dwarfs as a test of DM models: WDM vs. CDM
We use high resolution HydroN-Body cosmological simulations to compare the
assembly and evolution of a small field dwarf (stellar mass ~ 10
M, total mass 10 M in dominated CDM and 2keV WDM
cosmologies. We find that star formation (SF) in the WDM model is reduced and
delayed by 1-2 Gyr relative to the CDM model, independently of the details of
SF and feedback. Independent of the DM model, but proportionally to the SF
efficiency, gas outflows lower the central mass density through `dynamical
heating', such that all realizations have circular velocities 20kms at
500pc, in agreement with local kinematic constraints. As a result of
dynamical heating, older stars are less centrally concentrated than younger
stars, similar to stellar population gradients observed in nearby dwarf
galaxies. Introducing an important diagnostic of SF and feedback models, we
translate our simulations into artificial color-magnitude diagrams and star
formation histories in order to directly compare to available observations. The
simulated galaxies formed most of their stars in many 10 Myr long bursts.
The CDM galaxy has a global SFH, HI abundance and Fe/H and alpha-elements
distribution well matched to current observations of dwarf galaxies. These
results highlight the importance of directly including `baryon physics' in
simulations when 1) comparing predictions of galaxy formation models with the
kinematics and number density of local dwarf galaxies and 2) differentiating
between CDM and non-standard models with different DM or power spectra.Comment: 13 pages including Appendix on Color Magnitude Diagrams. Accepted by
MNRAS. Added one plot and details on ChaNGa implementation. Reduced number of
citations after editorial reques
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