4,598 research outputs found
Increased elastase sensitivity and decreased intramolecular interactions in the more transmissible 501Y.V1 and 501Y.V2 SARS-CoV-2 variants' spike protein-an in silico analysis.
Two SARS-CoV-2 variants of concern showing increased transmissibility relative to the Wuhan virus have recently been identified. Although neither variant appears to cause more severe illness nor increased risk of death, the faster spread of the virus is a major threat. Using computational tools, we found that the new SARS-CoV-2 variants may acquire an increased transmissibility by increasing the propensity of its spike protein to expose the receptor binding domain via proteolysis, perhaps by neutrophil elastase and/or via reduced intramolecular interactions that contribute to the stability of the closed conformation of spike protein. This information leads to the identification of potential treatments to avert the imminent threat of these more transmittable SARS-CoV-2 variants
Numerical evidence for `multi-scalar stars'
We present a class of general relativistic soliton-like solutions composed of
multiple minimally coupled, massive, real scalar fields which interact only
through the gravitational field. We describe a two-parameter family of
solutions we call ``phase-shifted boson stars'' (parameterized by central
density rho_0 and phase delta), which are obtained by solving the ordinary
differential equations associated with boson stars and then altering the phase
between the real and imaginary parts of the field. These solutions are similar
to boson stars as well as the oscillating soliton stars found by Seidel and
Suen [E. Seidel and W.M. Suen, Phys. Rev. Lett. 66, 1659 (1991)]; in
particular, long-time numerical evolutions suggest that phase-shifted boson
stars are stable. Our results indicate that scalar soliton-like solutions are
perhaps more generic than has been previously thought.Comment: Revtex. 4 pages with 4 figures. Submitted to Phys. Rev.
A first-in-human study of AMG 208, an oral MET inhibitor, in adult patients with advanced solid tumors.
BackgroundThis first-in-human study evaluated AMG 208, a small-molecule MET inhibitor, in patients with advanced solid tumors.MethodsThree to nine patients were enrolled into one of seven AMG 208 dose cohorts (25, 50, 100, 150, 200, 300, and 400 mg). Patients received AMG 208 orally on days 1 and days 4-28 once daily. The primary objectives were to evaluate the safety, tolerability, pharmacokinetics, and maximum tolerated dose (MTD) of AMG 208.ResultsFifty-four patients were enrolled. Six dose-limiting toxicities were observed: grade 3 increased aspartate aminotransferase (200 mg), grade 3 thrombocytopenia (200 mg), grade 4 acute myocardial infarction (300 mg), grade 3 prolonged QT (300 mg), and two cases of grade 3 hypertension (400 mg). The MTD was not reached. The most frequent grade ≥3 treatment-related adverse event was anemia (n = 3) followed by hypertension, prolonged QT, and thrombocytopenia (two patients each). AMG 208 exposure increased linearly with dose; mean plasma half-life estimates were 21.4-68.7 hours. One complete response (prostate cancer) and three partial responses (two in prostate cancer, one in kidney cancer) were observed.ConclusionsIn this study, AMG 208 had manageable toxicities and showed evidence of antitumor activity, particularly in prostate cancer
Experimental identification of non-pointlike dark-matter candidates
We show that direct dark matter detection experiments can distinguish between
pointlike and non-pointlike dark-matter candidates. The shape of the nuclear
recoil energy spectrum from pointlike dark-matter particles, e.g., neutralinos,
is determined by the velocity distribution of dark matter in the galactic halo
and by nuclear form factors. In contrast, typical cross sections of
non-pointlike dark matter, for example, Q-balls, have a new form factor, which
decreases rapidly with the recoil energy. Therefore, a signal from
non-pointlike dark matter is expected to peak near the experimental threshold
and to fall off rapidly at higher energies. Although the width of the signal is
practically independent of the dark matter velocity dispersion, its height is
expected to exhibit an annual modulation due to the changes in the dark matter
flux.Comment: 4 pages; minor changes, references adde
Structured information extraction from complex scientific text with fine-tuned large language models
Intelligently extracting and linking complex scientific information from
unstructured text is a challenging endeavor particularly for those
inexperienced with natural language processing. Here, we present a simple
sequence-to-sequence approach to joint named entity recognition and relation
extraction for complex hierarchical information in scientific text. The
approach leverages a pre-trained large language model (LLM), GPT-3, that is
fine-tuned on approximately 500 pairs of prompts (inputs) and completions
(outputs). Information is extracted either from single sentences or across
sentences in abstracts/passages, and the output can be returned as simple
English sentences or a more structured format, such as a list of JSON objects.
We demonstrate that LLMs trained in this way are capable of accurately
extracting useful records of complex scientific knowledge for three
representative tasks in materials chemistry: linking dopants with their host
materials, cataloging metal-organic frameworks, and general
chemistry/phase/morphology/application information extraction. This approach
represents a simple, accessible, and highly-flexible route to obtaining large
databases of structured knowledge extracted from unstructured text. An online
demo is available at http://www.matscholar.com/info-extraction
The H2 velocity structure of inner knots in HH 212: asymmetries and rotation
High-resolution R~50 000 long-slit spectroscopy of the inner knots of the
highly symmetrical protostellar outflow HH 212 was obtained in the 1-0 S(1)
line of H2 at 2.12 micron with a spatial resolution of ~0.45 arcsec. At the
resulting velocity resolution of ~6 km s-1, multiple slit oriented observations
of the northern first knot NK1 clearly show double-peaked line profiles
consistent with either a radiative bow shock or dual (forward and reverse)
shocks. In contrast, the velocity distribution of the southern first knot SK1
remains single-peaked, suggesting a significantly lower jet velocity and
possibly a different density variation in the jet pulses in the southern flow
compared to the northern flow. Comparison with a semi-empirical analytical
model of bow shock emission allows us to constrain parameters such as the bow
inclination to the line of sight, the bow shock and jet velocities for each
flow. Although a few features are not reproduced by this model, it confirms the
presence of several dynamical and kinematical asymmetries between opposite
sides of the HH 212 bipolar jet. The position-velocity diagrams of both knots
exhibit complex dynamics that are broadly consistent with emission from a bow
shock and/or jet shock, which does not exclude jet rotation, although a clear
signature of jet rotation in HH 212 is missing. Alternative interpretations of
the variation of radial velocity across these knots, such as a variation in the
jet orientation, as well as for the velocity asymmetries between the flows, are
also considered. The presence of a correlation between flow velocity and
collimation in each flow is suggested.Comment: Accepted for publication in Astronomy and Astrophysics, 16 page
Two-Level Systems in Nucleated and Non-Nucleated Epitaxial alpha-Tantalum films
Building usefully coherent superconducting quantum processors depends on
reducing losses in their constituent materials. Tantalum, like niobium, has
proven utility as the primary superconducting layer within highly coherent
qubits. But, unlike Nb, high temperatures are typically used to stabilize the
desirable body-centered-cubic phase, alpha-Ta, during thin film deposition. It
has long been known that a thin Nb layer permits the room-temperature
nucleation of alpha-Ta, although neither an epitaxial process nor few-photon
microwave loss measurements have been reported for Nb-nucleated Ta films prior
to this study. We compare resonators patterned from Ta films grown at high
temperature (500 {\deg}C) and films nucleated at room temperature, in order to
understand the impact of crystalline order on quantum coherence. In both cases,
films grew with Al2O3 (001) || Ta (110) indicating that the epitaxial
orientation is independent of temperature and is preserved across the Nb/Ta
interface. We use conventional low-power spectroscopy to measure two level
system (TLS) loss, as well as an electric-field bias technique to measure the
effective dipole moments of TLS in the surfaces of resonators. In our
measurements, Nb-nucleated Ta resonators had greater loss tangent (1.5 +/- 0.1
x 10^-5) than non-nucleated (5 +/- 1 x 10^-6) in approximate proportion to
defect densities as characterized by X-ray diffraction (0.27 {\deg} vs 0.18
{\deg} [110] reflection width) and electron microscopy (30 nm vs 70 nm domain
size). The dependence of the loss tangent on domain size indicates that the
development of more ordered Ta films is likely to lead to improvements in qubit
coherence times. Moreover, low-temperature alpha-Ta epitaxy may enable the
growth of new, microstate-free heterostructures which would not withstand high
temperature processing
Global embeddings of scalar-tensor theories in (2+1)-dimensions
We obtain (3+3)- or (3+2)-dimensional global flat embeddings of four
uncharged and charged scalar-tensor theories with the parameters B or L in the
(2+1)-dimensions, which are the non-trivially modified versions of the
Banados-Teitelboim-Zanelli (BTZ) black holes. The limiting cases B=0 or L=0
exactly are reduced to the Global Embedding Minkowski Space (GEMS) solution of
the BTZ black holes.Comment: 19 pages, 2 figure
Comparative Study Of High Temperature Workability OF ZM21 And AZ31 Magnesium Alloys
High temperature regime, 300-450?C for Mg-Al-Zn alloys, is currently used in primary processing, such as rolling and extrusion, as well as for secondary operation like forging. The knowledge of temperature and strain rate proper combination (processing window) as well as the microstructure evolution occurring during hot deformation clarifies the relationships between forming variables and final properties of components. Numerous data on AZ31 and few other Mg-Al alloys, produced by laboratory testing, are available in the scientific and technical literature. The ZM21, Mg-2Zn-1Mn, by contrast, is characterized by absolute lack of scientific data. In the alloy the addition of manganese, by suppressing the formation of beta phase, increases the solidus temperature that results in the larger processing window than in AZ31. The benefit requires extensive analysis aimed at optimizing the deformation variables that affect the microstructure refinement under dynamic and static recrystallization. The high-temperature plastic deformation and the microstructure evolution of the ZM21 were thus investigated in the temperature range between 200 and 500?C and results were analysed and compared with those of a conventional heat-treated AZ31
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