409 research outputs found
Age regression from soft aligned face images using low computational resources
The initial step in most facial age estimation systems consists of accurately aligning a model to the output of a face detector (e.g. an Active Appearance Model). This fitting process is very expensive in terms of computational resources and prone to get stuck in local minima. This makes it impractical for analysing faces in resource limited computing devices. In this paper we build a face age regressor that is able to work directly on faces cropped using a state-of-the-art face detector. Our procedure uses K nearest neighbours (K-NN) regression with a metric based on a properly tuned Fisher Linear Discriminant Analysis (LDA) projection matrix. On FG-NET we achieve a state-of-the-art Mean Absolute Error (MAE) of 5.72 years with manually aligned faces. Using face images cropped by a face detector we get a MAE of 6.87 years in the same database. Moreover, most of the algorithms presented in the literature have been evaluated on single database experiments and therefore, they report optimistically biased results. In our cross-database experiments we get a MAE of roughly 12 years, which would be the expected performance in a real world application
Treatment of competition between complete fusion and quasifission in collisions of heavy nuclei
A model of competition between complete fusion and quasifission channels in
fusion of two massive nuclei is extended to include the influence of
dissipative effects on the dynamics of nuclear fusion. By using the
multidimensional Kramers-type stationary solution of the Fokker-Planck
equation, the fusion rate through the inner fusion barrier in mass asymmetry is
studied. Fusion probabilities in symmetric 90Zr+90Zr, 100Mo+100Mo, 110Pd+110Pd,
136Xe+136Xe, almost symmetric 86Kr+136Xe and 110Pd+136Xe reactions are
calculated. An estimation of the fusion probabilities is given for asymmetrical
62Ni+208Pb, 70Zn+208Pb, 82Se+208Pb, and 48Ca+244Pu reactions used for the
synthesis of new superheavy elements.Comment: 29 pages, LaTeX, including 7 postscript figures, to appear in Nucl.
Phys.
Conformal fields in the pp-wave limit
The pp-wave (Penrose limit) in conformal field theory can be viewed as a
special contraction of the unitary representations of the conformal group. We
study the kinematics of conformal fields in this limit in a geometric approach
where the effect of the contraction can be visualized as an expansion of
space-time. We discuss the two common models of space-time as carrier spaces
for conformal fields: One is the usual Minkowski space and the other is the
coset of the conformal group over its maximal compact subgroup. We show that
only the latter manifold and the corresponding conformal representation theory
admit a non-singular contraction limit. We also address the issue of
correlation functions of conformal fields in the pp-wave limit. We show that
they have a well-defined contraction limit if their space-time dependence
merges with the dependence on the coordinates of the R symmetry group. This is
a manifestation of the fact that in the limit the space-time and R symmetries
become indistinguishable. Our results might find applications in actual
calculations of correlation functions of composite operators in N=4 super
Yang-Mills theory.Comment: LaTex, 32 pages, 1 figure, discussion of correlation functions
extended; some corrections made; references adde
New Approach to GUTs
We introduce a new string-inspired approach to the subject of grand
unification which allows the GUT scale to be small, \lesssim 200 TeV, so that
it is within the reach of {\em conceivable} laboratory accelerated colliding
beam devices. The key ingredient is a novel use of the heterotic string
symmetry group physics ideas to render baryon number violating effects small
enough to have escaped detection to date. This part of the approach involves
new unknown parameters to be tested experimentally. A possible hint at the
existence of these new parameters may already exist in the EW precision data
comparisons with the SM expectations.Comment: 8 pages; improved text and references, note added; extended text, 1
figure added; extended text for publication in Eur. Phys. Journal
Unification of couplings and soft supersymmetry breaking terms in 4D superstring models
We consider the predictions for the hierarchy of mass scales, the fine
structure constant, the radii of compactification and the soft SUSY breaking
terms which follow if SUSY breaking is triggered by a gaugino condensate.Comment: 16 pages (LaTeX) Oxford preprint OUTP-93-32
Neutron Structure Function and A=3 Mirror Nuclei
We investigate deep inelastic scattering from He-3 and H-3 within a
conventional convolution treatment of binding and Fermi motion effects. Using
realistic Faddeev wave functions together with a nucleon spectral function, we
demonstrate that the free neutron structure function can be extracted in
deep-inelastic scattering from A=3 mirror nuclei, with nuclear effects
canceling to within 2% for x < 0.85.Comment: 13 pages, 4 figures, version to appear in Phys. Lett.
Spin fluctuations in nearly magnetic metals from ab-initio dynamical spin susceptibility calculations:application to Pd and Cr95V5
We describe our theoretical formalism and computational scheme for making
ab-initio calculations of the dynamic paramagnetic spin susceptibilities of
metals and alloys at finite temperatures. Its basis is Time-Dependent Density
Functional Theory within an electronic multiple scattering, imaginary time
Green function formalism. Results receive a natural interpretation in terms of
overdamped oscillator systems making them suitable for incorporation into spin
fluctuation theories. For illustration we apply our method to the nearly
ferromagnetic metal Pd and the nearly antiferromagnetic chromium alloy Cr95V5.
We compare and contrast the spin dynamics of these two metals and in each case
identify those fluctuations with relaxation times much longer than typical
electronic `hopping times'Comment: 21 pages, 9 figures. To appear in Physical Review B (July 2000
Elastic electron deuteron scattering with consistent meson exchange and relativistic contributions of leading order
The influence of relativistic contributions to elastic electron deuteron
scattering is studied systematically at low and intermediate momentum transfers
( fm). In a -expansion, all leading order
relativistic -exchange contributions consistent with the Bonn OBEPQ models
are included. In addition, static heavy meson exchange currents including boost
terms and lowest order -currents are considered. Sizeable
effects from the various relativistic two-body contributions, mainly from
-exchange, have been found in form factors, structure functions and the
tensor polarization . Furthermore, static properties, viz. magnetic
dipole and charge quadrupole moments and the mean square charge radius are
evaluated.Comment: 15 pages Latex including 5 figures, final version accepted for
publication in Phys.Rev.C Details of changes: (i) The notation of the curves
in Figs. 1 and 2 have been clarified with respect to left and right panels.
(ii) In Figs. 3 and 4 an experimental point for T_20 has been added and a
corresponding reference [48] (iii) At the end of the text we have added a
paragraph concerning the quality of the Bonn OBEPQ potential
Path Integral Monte Carlo Approach to the U(1) Lattice Gauge Theory in (2+1) Dimensions
Path Integral Monte Carlo simulations have been performed for U(1) lattice
gauge theory in (2+1) dimensions on anisotropic lattices. We extractthe static
quark potential, the string tension and the low-lying "glueball" spectrum.The
Euclidean string tension and mass gap decrease exponentially at weakcoupling in
excellent agreement with the predictions of Polyakov and G{\" o}pfert and Mack,
but their magnitudes are five times bigger than predicted. Extrapolations are
made to the extreme anisotropic or Hamiltonian limit, and comparisons are made
with previous estimates obtained in the Hamiltonian formulation.Comment: 12 pages, 16 figure
Deconfining Phase Transition as a Matrix Model of Renormalized Polyakov Loops
We discuss how to extract renormalized from bare Polyakov loops in SU(N)
lattice gauge theories at nonzero temperature in four spacetime dimensions.
Single loops in an irreducible representation are multiplicatively renormalized
without mixing, through a renormalization constant which depends upon both
representation and temperature. The values of renormalized loops in the four
lowest representations of SU(3) were measured numerically on small, coarse
lattices. We find that in magnitude, condensates for the sextet and octet loops
are approximately the square of the triplet loop. This agrees with a large
expansion, where factorization implies that the expectation values of loops in
adjoint and higher representations are just powers of fundamental and
anti-fundamental loops. For three colors, numerically the corrections to the
large relations are greatest for the sextet loop, ; these
represent corrections of for N=3. The values of the renormalized
triplet loop can be described by an SU(3) matrix model, with an effective
action dominated by the triplet loop. In several ways, the deconfining phase
transition for N=3 appears to be like that in the matrix model of
Gross and Witten.Comment: 24 pages, 7 figures; v2, 27 pages, 12 figures, extended discussion
for clarity, results unchange
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