765 research outputs found
“Cowboy, Paladin, Hero?”: Being Boys and Men in David Foster Wallace’s The Pale King
Often aligned with post-postmodernism, David Foster Wallace’s later work retreats from the ironic detachment and cynicism of postmodernism in favor of a more sincere approach to writing. This is especially evident in his posthumous novel, The Pale King, a work dealing with what it means to be human in the Information Age. After locating the novel’s setting within a recent history of American masculinity and work, this paper examines several of the novel’s male characters as they struggle to be fully realized boys and men, concluding that The Pale King is Wallace’s final statement that enduring the ennui of modern life is admirable, even heroic
Factors associated with suicide among African American adult men: a systematic review of the literature
http://dx.doi.org/10.1016/j.jomh.2008.09.01
Explicit Integration of Extremely-Stiff Reaction Networks: Quasi-Steady-State Methods
A preceding paper demonstrated that explicit asymptotic methods generally
work much better for extremely stiff reaction networks than has previously been
shown in the literature. There we showed that for systems well removed from
equilibrium explicit asymptotic methods can rival standard implicit codes in
speed and accuracy for solving extremely stiff differential equations. In this
paper we continue the investigation of systems well removed from equilibrium by
examining quasi-steady-state (QSS) methods as an alternative to asymptotic
methods. We show that for systems well removed from equilibrium, QSS methods
also can compete with, or even exceed, standard implicit methods in speed, even
for extremely stiff networks, and in many cases give somewhat better
integration speed than for asymptotic methods. As for asymptotic methods, we
will find that QSS methods give correct results, but with non-competitive
integration speed as equilibrium is approached. Thus, we shall find that both
asymptotic and QSS methods must be supplemented with partial equilibrium
methods as equilibrium is approached to remain competitive with implicit
methods.Comment: Updated reference
Probing the interface in a human co-chaperonin heptamer: residues disrupting oligomeric unfolded state identified
BACKGROUND: The co-chaperonin protein 10 (cpn10) assists cpn60 in the folding of nonnative polypeptides in a wide range of organisms. All known cpn10 molecules are heptamers of seven identical subunits that are linked together by β-strand interactions at a large and flexible interface. Unfolding of human mitochondrial cpn10 in urea results in an unfolded heptameric state whereas GuHCl additions result in unfolded monomers. To address the role of specific interface residues in the assembly of cpn10 we prepared two point-mutated variants, in each case removing a hydrophobic residue positioned at the subunit-subunit interface. RESULTS: Replacing valine-100 with a glycine (Val100Gly cpn10) results in a wild-type-like protein with seven-fold symmetry although the thermodynamic stability is decreased and the unfolding processes in urea and GuHCl both result in unfolded monomers. In sharp contrast, replacing phenylalanine-8 with a glycine (Phe8Gly cpn10) results in a protein that has lost the ability to assemble. Instead, this protein exists mostly as unfolded monomers. CONCLUSIONS: We conclude that valine-100 is a residue important to adopt an oligomeric unfolded state but it does not affect the ability to assemble in the folded state. In contrast, phenylalanine-8 is required for both heptamer assembly and monomer folding and therefore this mutation results in unfolded monomers at physiological conditions. Despite the plasticity and large size of the cpn10 interface, our observations show that isolated interface residues can be crucial for both the retention of a heptameric unfolded structure and for subunit folding
Bifunctional [c2]Daisy-Chains and Their Incorporation into Mechanically Interlocked Polymers
A strategy for the formation of mechanically interlocked polymers is presented. Ring-closing olefin metathesis has been shown to provide a very high yielding route to [c2]daisy-chains suitably functionalized to allow their one-step conversion to bisolefins which can be used as monomers in ADMET polymerizations to afford mechanically interlocked polymers. Metathesis, in two different guises is making a hitherto unreachable goal in synthesis a reality
Solution of the Nuclear Shell Model by Symmetry-Dictated Truncation
The dynamical symmetries of the Fermion Dynamical Symmetry Model are used as
a principle of truncation for the spherical shell model. Utilizing the usual
principle of energy-dictated truncation to select a valence space, and
symmetry-dictated truncation to select a collective subspace of that valence
space, we are able to reduce the full shell model space to one of manageable
dimensions with modern supercomputers, even for the heaviest nuclei. The
resulting shell model then consists of diagonalizing an effective Hamiltonian
within the restricted subspace. This theory is not confined to any symmetry
limits, and represents a full solution of the original shell model if the
appropriate effective interaction of the truncated space can be determined. As
a first step in constructing that interaction, we present an empirical
determination of its matrix elements for the collective subspace with no broken
pairs in a representative set of nuclei with . We demonstrate
that this effective interaction can be parameterized in terms of a few
quantities varying slowly with particle number, and is capable of describing a
broad range of low-energy observables for these nuclei. Finally we give a brief
discussion of extending these methods to include a single broken collective
pair.Comment: invited paper for J. Phys. G, 57 pages, Latex, 18 figures a macro are
available under request at [email protected]
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