1,710 research outputs found
Chiral molecule adsorption on helical polymers
We present a lattice model for helicity induction on an optically inactive
polymer due to the adsorption of exogenous chiral amine molecules. The system
is mapped onto a one-dimensional Ising model characterized by an on-site
polymer helicity variable and an amine occupancy one. The equilibrium
properties are analyzed at the limit of strong coupling between helicity
induction and amine adsorption and that of non-interacting adsorbant molecules.
We discuss our results in view of recent experimental results
Noncommutative SO(n) and Sp(n) Gauge Theories
We study the generalization of noncommutative gauge theories to the case of
orthogonal and symplectic groups. We find out that this is possible, since we
are allowed to define orthogonal and symplectic subgroups of noncommutative
unitary gauge transformations even though the gauge potentials and gauge
transformations are not valued in the orthogonal and symplectic subalgebras of
the Lie algebra of antihermitean matrices. Our construction relies on an
antiautomorphism of the basic noncommutative algebra of functions which
generalizes the charge conjugation operator of ordinary field theory. We show
that the corresponding noncommutative picture from low energy string theory is
obtained via orientifold projection in the presence of a non-trivial NSNS
B-field.Comment: 17 pages; considerations about fermions added and some minor change
Divergence Cancellation and Loop Corrections in String Field Theory on a Plane Wave Background
We investigate the one-loop energy shift E to certain two-impurity string
states in light-cone string field theory on a plane wave background. We find
that there exist logarithmic divergences in the sums over intermediate mode
numbers which cancel between the cubic Hamiltonian and quartic ``contact
term''. Analyzing the impurity non-conserving channel we find that the
non-perturbative, order g_2^2 sqrt(lambda') contribution to E/mu predicted in
hep-th/0211220 is in fact an artifact of these logarithmic divergences and
vanishes with them, leaving an order g_2^2 lambda' contribution. Exploiting the
supersymmetry algebra, we present a form for the energy shift which appears to
be manifestly convergent and free of non-perturbative terms. We use this form
to argue that E/mu receives order g_2^2 lambda' contributions at every order in
intermediate state impurities.Comment: 27 pages; added references, acknowledgments, missing normalization in
equations 2.3 - 2.8, also cleaned up notation, and added a few footnote
Understanding the impact and tackling the burden of osteoarthritis for Aboriginal and Torres Strait Islander people
Objective
The aim of this study was to understand and describe the lived experience of Aboriginal and Torres Strait Islander people with osteoarthritis.
Methods
Qualitative study guided by cultural security, which ensures that research is conducted in a way that will not compromise the cultural values, beliefs, and expectations of Aboriginal and Torres Strait Islander people. Participants were purposively sampled through the networks of project staff. Research yarns (a cultural form of conversation used as a data gathering tool) were conducted with 25 Aboriginal and Torres Strait Islander adults with self-reported osteoarthritis in Western Australia and Victoria, Australia. Data were analyzed using a framework approach and presented through composite storytelling (hypothetical stories representing an amalgam of participants’ experiences).
Results
Two composite stories were constructed to reflect themes relating to beliefs and knowledge, impact, coping, and health care experiences. Common beliefs held by participants were that osteoarthritis is caused by previous physically active lifestyles. Many participants feared for their future, increasing disability and needing a wheelchair. Pain associated with osteoarthritis impacted daily activities, sleep, work, family, and social life and cultural activities. Multidimensional impacts were often experienced within complex health or life circumstances and associated with increased anxiety and depression. Most participants reported negative health care experiences, characterized by poor patient–provider communication.
Conclusion
Our findings highlight that osteoarthritis is a multidimensional issue for Aboriginal and Torres Strait Islander people that permeates all aspects of life and highlights the need for integrated, multidisciplinary care that is culturally informed and individualized to patient need
Plate Wave Propagation in Transversely Isotropic Materials
In this work, the modes of plate wave propagation in a fiber reinforced com posite (assumed to be transversely isotropic) were investigated. The waves were modeled as harmonic plane waves propagating in the plane of an infinite plate whose bounding sur faces were assumed to be stress free. A numerical analysis procedure was developed to calculate the dispersion relationships for plate waves propagating in arbitrary directions in the plate. Particle displacements and stress distributions were calculated for several im portant propagation modes. Possible applications to nondestructive testing of composites are discussed.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
M-flation: Inflation From Matrix Valued Scalar Fields
We propose an inflationary scenario, M-flation, in which inflation is driven
by three hermitian matrices . The inflation
potential of our model, which is strongly motivated from string theory, is
constructed from and their commutators. We show that one can
consistently restrict the classical dynamics to a sector in which the
are proportional to the irreducible representations of SU(2). In
this sector our model effectively behaves as an N-flation model with
number of fields and the effective inflaton field has a super-Planckian field
value. Furthermore, the fine-tunings associated with unnaturally small
couplings in the chaotic type inflationary scenarios are removed. Due to the
matrix nature of the inflaton fields there are extra scalar fields in
the dynamics. These have the observational effects such as production of
iso-curvature perturbations on cosmic microwave background. Moreover, the
existence of these extra scalars provides us with a natural preheating
mechanism and exit from inflation. As the effective inflaton field can traverse
super-Planckian distances in the field space, the model is capable of producing
a considerable amount of gravity waves that can be probed by future CMB
polarization experiments such as PLANCK, QUIET and CMBPOL.Comment: minor changes, the counting of the alpha and beta modes are
corrected, references adde
Graded Poisson-Sigma Models and Dilaton-Deformed 2D Supergravity Algebra
Fermionic extensions of generic 2d gravity theories obtained from the graded
Poisson-Sigma model (gPSM) approach show a large degree of ambiguity. In
addition, obstructions may reduce the allowed range of fields as given by the
bosonic theory, or even prohibit any extension in certain cases. In our present
work we relate the finite W-algebras inherent in the gPSM algebra of
constraints to algebras which can be interpreted as supergravities in the usual
sense (Neuveu-Schwarz or Ramond algebras resp.), deformed by the presence of
the dilaton field. With very straightforward and natural assumptions on them
--like demanding rigid supersymmetry in a certain flat limit, or linking the
anti-commutator of certain fermionic charges to the Hamiltonian constraint-- in
the ``genuine'' supergravity obtained in this way the ambiguities disappear, as
well as the obstructions referred to above. Thus all especially interesting
bosonic models (spherically reduced gravity, the Jackiw-Teitelboim model etc.)\
under these conditions possess a unique fermionic extension and are free from
new singularities. The superspace supergravity model of Howe is found as a
special case of this supergravity action. For this class of models the relation
between bosonic potential and prepotential does not introduce obstructions as
well.Comment: 22 pages, LaTeX, JHEP class. v3: Final version, to appear in JHE
U(2)-like Flavor Symmetries and Approximate Bimaximal Neutrino Mixing
Models involving a U(2) flavor symmetry, or any of a number of its
non-Abelian discrete subgroups, can explain the observed hierarchy of charged
fermion masses and CKM angles. It is known that a large neutrino mixing angle
connecting second and third generation fields may arise via the seesaw
mechanism in these models, without a fine tuning of parameters. Here we show
that it is possible to obtain approximate bimaximal mixing in a class of models
with U(2)-like Yukawa textures. We find a minimal form for Dirac and Majorana
neutrino mass matrices that leads to two large mixing angles, and show that our
result can quantitatively explain atmospheric neutrino oscillations while
accommodating the favored, large angle MSW solution to the solar neutrino
problem. We demonstrate that these textures can arise in models by presenting a
number of explicit examples.Comment: 20 pages RevTex4, 2 figure
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