1,585 research outputs found
A Look-Ahead Feature - Sow Stalls for Indiviudal Feeding
Overfeeding sows and gilts during gestation is a common mismanagement practice. Here\u27s how concrete stalls were built for individual feeding to assure a minimum, but adequate, amount of feed for each animal
Probabilistic Volcanic Ash Hazard Analysis (PVAHA) II: assessment of the Asia-Pacific region using VAPAH
Monthly mean wind direction and wind speed aggregated for a 64-year period from NCEP reanalysis data for 60 NCEP grid points used for the Asia-Pacific case study. (CSV 1 kb
Limit on Lorentz and CPT Violation of the Neutron Using a Two-Species Noble-Gas Maser
A search for sidereal variations in the frequency difference between co-located 129-Xe and 3-He Zeeman masers sets the most stringent limit to date on leading-order Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 10^{-31} GeV
Bound on Lorentz- and CPT-Violating Boost Effects for the Neutron
A search for an annual variation of a daily sidereal modulation of the
frequency difference between co-located Xe and He Zeeman
masers sets a stringent limit on boost-dependent Lorentz and CPT violation
involving the neutron, consistent with no effect at the level of 150 nHz. In
the framework of the general Standard-Model Extension, the present result
provides the first clean test for the fermion sector of the symmetry of
spacetime under boost transformations at a level of GeV.Comment: 4 pages, 1 figur
Stability, Causality, and Lorentz and CPT Violation
Stability and causality are investigated for quantum field theories
incorporating Lorentz and CPT violation. Explicit calculations in the quadratic
sector of a general renormalizable lagrangian for a massive fermion reveal that
no difficulty arises for low energies if the parameters controlling the
breaking are small, but for high energies either energy positivity or
microcausality is violated in some observer frame. However, this can be avoided
if the lagrangian is the sub-Planck limit of a nonlocal theory with spontaneous
Lorentz and CPT violation. Our analysis supports the stability and causality of
the Lorentz- and CPT-violating standard-model extension that would emerge at
low energies from spontaneous breaking in a realistic string theory.Comment: 20 pages, accepted for publication in Physical Review
Identification and characterization of the mouse nuclear export factor (Nxf) family members
TAP/hNXF1 is a key factor that mediates general cellular mRNA export from the nucleus, and its orthologs are structurally and functionally conserved from yeast to humans. Metazoans encode additional proteins that share homology and domain organization with TAP/hNXF1, suggesting their participation in mRNA metabolism; however, the precise role(s) of these proteins is not well understood. Here, we found that the human mRNA export factor hNXF2 is specifically expressed in the brain, suggesting a brain-specific role in mRNA metabolism. To address the roles of additional NXF factors, we have identified and characterized the two Nxf genes, Nxf2 and Nxf7, which together with the TAP/hNXF1's ortholog Nxf1 comprise the murine Nxf family. Both mNXF2 and mNXF7 have a domain structure typical of the NXF family. We found that mNXF2 protein is expressed during mouse brain development. Similar to TAP/hNXF1, the mNXF2 protein is found in the nucleus, the nuclear envelope and cytoplasm, and is an active mRNA export receptor. In contrast, mNXF7 localizes exclusively to cytoplasmic granules and, despite its overall conserved sequence, lacks mRNA export activity. We concluded that mNXF2 is an active mRNA export receptor similar to the prototype TAP/hNXF1, whereas mNXF7 may have a more specialized role in the cytoplasm
Clock-Comparison Tests of Lorentz and CPT Symmetry in Space
Clock-comparison experiments conducted in space can provide access to many
unmeasured coefficients for Lorentz and CPT violation. The orbital
configuration of a satellite platform and the relatively large velocities
attainable in a deep-space mission would permit a broad range of tests with
Planck-scale sensitivity.Comment: 4 page
Cosmological Constraints on Lorentz Violation in Electrodynamics
Infrared, optical, and ultraviolet spectropolarimetry of cosmological sources
is used to constrain the pure electromagnetic sector of a general
Lorentz-violating standard-model extension. The coefficients for Lorentz
violation are bounded to less than 3x10^{-32}.Comment: 4 pages, accepted for publication in Physical Review Letter
Lack of uniqueness for weak solutions of the incompressible porous media equation
In this work we consider weak solutions of the incompressible 2-D porous
media equation. By using the approach of De Lellis-Sz\'ekelyhidi we prove
non-uniqueness for solutions in in space and time.Comment: 23 pages, 2 fugure
Spacetime-varying couplings and Lorentz violation
Spacetime-varying coupling constants can be associated with violations of
local Lorentz invariance and CPT symmetry. An analytical supergravity cosmology
with time-varying fine-structure constant provides an explicit example.
Estimates are made for some experimental constraints.Comment: 4 page
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