803 research outputs found
Nuclides as a liquid phase of chiral perturbation theory I: emergence of pion-less SU(2) PT
The Standard Model of particle physics, augmented with neutrino mixing, is at
least very nearly the complete theory of interactions of known particles at
energies accessible to Nature on Earth. Candidate effective theories of nuclear
structure must therefore reflect SM symmetries, especially the chiral global
symmetry of two-massless-quark QCD. For ground-state
nuclei, SU(2) chiral perturbation theory (XPT) enables perturbation in inverse
powers of , with analytic operators renormalized to
all loop orders. We show that pion-less "Static Chiral Nucleon Liquids" (SXNL)
emerge as a liquid phase of SU(2) XPT of protons, neutrons and 3
Nambu-Goldstone boson pions. Far-IR pions decouple from SXNL, simplifying the
derivation of saturated nuclear matter and microscopic liquid drops
(ground-state nuclides). We trace to the global symmetries of
two-massless-quark QCD the power of pion-less SU(2) XPT to capture experimental
ground-state properties of certain nuclides with even parity, spin zero, even
proton number Z, and neutron number N.
We derive the SXNL effective SU(2) XPT Lagrangian, including all order
operators. These include: all 4-nucleon
operators that survive Fierz rearrangement in the non-relativistic limit, and
effective Lorentz-vector iso-vector neutral "-exchange" operators. SXNL
motivate nuclear matter as non-topological solitons at zero pressure: the
Nuclear Liquid Drop Model and Bethe-Weizsacker Semi-Empirical Mass Formula
emerge in an explicit Thomas-Fermi construction provided in the companion
paper. For chosen nuclides, nuclear Density Functional and Skyrme models are
justified to order . We conjecture that inclusion of
higher order operators will result in accurate "natural" Skyrme, No-Core-Shell,
and neutron star models
The Value of Work: A Case for Promoting Christian Service Opportunities to College Students
The purpose of this paper is to discuss the historical evolution of attitudes toward work, the Protestant work ethic, a Biblical perspective on work, and to provide a rational for why Christian colleges should offer multiple service opportunities for students to help them integrate faith into their everyday lives
Macro Dark Matter
Dark matter is a vital component of the current best model of our universe,
CDM. There are leading candidates for what the dark matter could be
(e.g. weakly-interacting massive particles, or axions), but no compelling
observational or experimental evidence exists to support these particular
candidates, nor any beyond-the-Standard-Model physics that might produce such
candidates. This suggests that other dark matter candidates, including ones
that might arise in the Standard Model, should receive increased attention.
Here we consider a general class of dark matter candidates with characteristic
masses and interaction cross-sections characterized in units of grams and
cm, respectively -- we therefore dub these macroscopic objects as Macros.
Such dark matter candidates could potentially be assembled out of Standard
Model particles (quarks and leptons) in the early universe. A combination of
Earth-based, astrophysical, and cosmological observations constrain a portion
of the Macro parameter space. A large region of parameter space remains, most
notably for nuclear-dense objects with masses in the range g and
g, although the lower mass window is closed
for Macros that destabilize ordinary matter.Comment: 13 pages, 1 table, 4 figures. Submitted to MNRAS. v3: corrected small
errors and a few points were made more clear, v4: included CMB bounds on dark
matter-photon coupling from Wilkinson et al. (2014) and references added.
Final revision matches published versio
Genomic Resources and Tools for Gene Function Analysis in Potato
Potato, a highly heterozygous tetraploid, is undergoing an exciting phase of genomics resource development. The potato research community has established extensive genomic resources, such as large expressed sequence tag (EST) data collections, microarrays and other expression profiling platforms, and large-insert genomic libraries. Moreover, potato will now benefit from a global potato physical mapping effort, which is serving as the underlying resource for a full potato genome sequencing project, now well underway. These tools and resources are having a major impact on potato breeding and genetics. The genome sequence will provide an invaluable comparative genomics resource for cross-referencing to the other Solanaceae, notably tomato, whose sequence is also being determined. Most importantly perhaps, a potato genome sequence will pave the way for the functional analysis of the large numbers of potato genes that await discovery. Potato, being easily transformable, is highly amenable to the investigation of gene function by biotechnological approaches. Recent advances in the development of Virus Induced Gene Silencing (VIGS) and related methods will facilitate rapid progress in the analysis of gene function in this important crop
Agent Performance and Customer Satisfaction
To fulfill its mission, Extension must develop programs that are relevant and high quality, and improve the lives of clients. Customer satisfaction surveys are used in Florida to collect data about these attributes. It is also important to understand how employee performance affects customer satisfaction. Our findings show that customer satisfaction was not significantly influenced by agent performance and that Florida Cooperative Extension benefits from the experience of its workforce. Given the importance of customer satisfaction as Extension\u27s performance measure for the Florida Legislature, we suggest that administrators should emphasize customer satisfaction as a major factor in employee performance scores
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