1,084 research outputs found
Petrous bone diagenesis: a multi-analytical approach
© 2019 Elsevier B.V. The discovery of petrous bone as an excellent repository for ancient biomolecules has been a turning point in biomolecular archaeology, especially in aDNA research, but excessive and uncontrolled sampling could result in loss of this valuable resource for future research. This study reports on the histological (optical microscopy), physical (FTIR-ATR), elemental (CHN) and biochemical (collagen and DNA analysis) preservation of 15 human petrous bones spanning from the c. 2100 BCE to 1850 CE. Through the combined application of a number of diagenetic parameters (general histological index; infrared splitting factor; carbonate/phosphate ratio; amide/phosphate ratio; col wt%; % C, % N and C/N of whole bone and collagen; % endogenous DNA), we provide new insights into petrous bone micromorphological characteristics and diagenesis, and new evidence to enhance screening practices for aDNA and collagen analysis.MJC was supported by Danish National Research Foundation (DNRF128) and KP from the Leverhulme Trust (PLP-2012-116). MEA thanks The Danish National Resarch Foundation (DNRF94), the Lundbeck Foundation, the University of Copehagen (KU2016 programme) and the Vellux Foundations (Villum Young Investigator programme). IK would like to thank Onassis Foundation (grant no. F ZL 047-1/2015-2016), Leventis Foundation and the Greek Archaeological Committee UK (GACUK)
Unstable Modes in Three-Dimensional SU(2) Gauge Theory
We investigate SU(2) gauge theory in a constant chromomagnetic field in three
dimensions both in the continuum and on the lattice. Using a variational method
to stabilize the unstable modes, we evaluate the vacuum energy density in the
one-loop approximation. We compare our theoretical results with the outcomes of
the numerical simulations.Comment: 24 pages, REVTEX 3.0, 3 Postscript figures included. (the whole
postscript file (text+figures) is available on request from
[email protected]
A Remark on the Renormalization Group Equation for the Penner Model
It is possible to extract values for critical couplings and gamma_string in
matrix models by deriving a renormalization group equation for the variation of
the of the free energy as the size N of the matrices in the theory is varied.
In this paper we derive a ``renormalization group equation'' for the Penner
model by direct differentiation of the partition function and show that it
reproduces the correct values of the critical coupling and gamma_string and is
consistent with the logarithmic corrections present for g=0,1.Comment: LaTeX, 5 pages, LPTHE-Orsay-94-5
Stochastic Quantization of Scalar Fields in Einstein and Rindler Spacetime
We consider the stochastic quantization method for scalar fields defined in a
curved manifold and also in a flat space-time with event horizon. The two-point
function associated to a massive self-interacting scalar field is evaluated, up
to the first order level in the coupling constant, for the case of an Einstein
and also a Rindler Euclidean metric, respectively. Its value for the asymptotic
limit of the Markov parameter is exhibited. The divergences therein are taken
care of by employing a covariant stochastic regularization
Species Doublers as Super Multiplets in Lattice Supersymmetry: Exact Supersymmetry with Interactions for D=1 N=2
We propose a new lattice superfield formalism in momentum representation
which accommodates species doublers of the lattice fermions and their bosonic
counterparts as super multiplets. We explicitly show that one dimensional N=2
model with interactions has exact Lie algebraic supersymmetry on the lattice
for all super charges. In coordinate representation the finite difference
operator is made to satisfy Leibnitz rule by introducing a non local product,
the ``star'' product, and the exact lattice supersymmetry is realized. The
standard momentum conservation is replaced on the lattice by the conservation
of the sine of the momentum, which plays a crucial role in the formulation.
Half lattice spacing structure is essential for the one dimensional model and
the lattice supersymmetry transformation can be identified as a half lattice
spacing translation combined with alternating sign structure. Invariance under
finite translations and locality in the continuum limit are explicitly
investigated and shown to be recovered. Supersymmetric Ward identities are
shown to be satisfied at one loop level. Lie algebraic lattice supersymmetry
algebra of this model suggests a close connection with Hopf algebraic exactness
of the link approach formulation of lattice supersymmetry.Comment: 34 pages, 2 figure
Confinement and the photon propagator in 3D compact QED: a lattice study in Landau gauge at zero and finite temperature
On the lattice we study the gauge boson propagator of three dimensional
compact QED in Landau gauge at zero and non-zero temperature. The
non-perturbative effects are taken into account by the generation of a mass, by
an anomalous dimension and by the photon wave function renormalization. All
these effects can be attributed to the monopoles: they are absent in the
propagator of the singularity-free part of the gauge field. We assess carefully
the Gribov copy problem for the propagator and the parameters emerging from the
fits.Comment: 25 pages, 32 figures, RevTeX 4; version in print in Phys. Rev. D;
typos and figures 5c and 7c correcte
Extended Dualization: a method for the Bosonization of Anomalous Fermion Systems in Arbitrary Dimension
The technique of extended dualization developed in this paper is used to
bosonize quantized fermion systems in arbitrary dimension in the low energy
regime. In its original (minimal) form, dualization is restricted to models
wherein it is possible to define a dynamical quantized conserved charge. We
generalize the usual dualization prescription to include systems with dynamical
non--conserved quantum currents. Bosonization based on this extended
dualization requires the introduction of an additional rank (scalar) field
together with the usual antisymmetric tensor field of rank . Our
generalized dualization prescription permits one to clearly distinguish the
arbitrariness in the bosonization from the arbitrariness in the quantization of
the system. We study the bosonization of four--fermion interactions with large
mass in arbitrary dimension. First, we observe that dualization permits one to
formally bosonize these models by invoking the bosonization of the free massive
Dirac fermion and adding some extra model--dependent bosonic terms. Secondly,
we explore the potential of extended dualization by considering the particular
case of \underbar{chiral} four--fermion interactions. Here minimal dualization
is inadequate for calculating the extra bosonic terms. We demonstrate the
utility of extended dualization by successfully completing the bosonization of
this chiral model. Finally, we consider two examples in two dimensions which
illuminate the utility of using extended dualization by showing how
quantization ambiguities in a fermionic theory propagate into the bosonized
version. An explicit parametrization of the quantization ambiguities of the
chiral current in the Chiral Schwinger model is obtained. Similarly, for the
sine--Gordon interaction in the massive Thirring model the quantizationComment: Revised version including major changes in section 3, to be published
in Phys. Rev.
Stochastic Quantization of Scalar Fields in de Sitter Spacetime
We consider the stochastic quantization method for scalar fields defined in a
curved manifold. The two-point function associated to a massive
self-interacting scalar field is evaluated, up to the first order level in the
coupling constant , for the case of de Sitter Euclidean metric. Its
value for the asymptotic limit of the Markov parameter is
exhibited. We discuss in detail the covariant stochastic regularization to
render the one-loop two-point function finite in the de Sitter Euclidean
metric
Duality symmetry, strong coupling expansion and universal critical amplitudes in two-dimensional \Phi^{4} field models
We show that the exact beta-function \beta(g) in the continuous 2D g\Phi^{4}
model possesses the Kramers-Wannier duality symmetry. The duality symmetry
transformation \tilde{g}=d(g) such that \beta(d(g))=d'(g)\beta(g) is
constructed and the approximate values of g^{*} computed from the duality
equation d(g^{*})=g^{*} are shown to agree with the available numerical
results. The calculation of the beta-function \beta(g) for the 2D scalar
g\Phi^{4} field theory based on the strong coupling expansion is developed and
the expansion of \beta(g) in powers of g^{-1} is obtained up to order g^{-8}.
The numerical values calculated for the renormalized coupling constant
g_{+}^{*} are in reasonable good agreement with the best modern estimates
recently obtained from the high-temperature series expansion and with those
known from the perturbative four-loop renormalization-group calculations. The
application of Cardy's theorem for calculating the renormalized isothermal
coupling constant g_{c} of the 2D Ising model and the related universal
critical amplitudes is also discussed.Comment: 16 pages, REVTeX, to be published in J.Phys.A:Math.Ge
- …