51,866 research outputs found
Fermion Generations and Mixing from Dualized Standard Model
We review a possible solution to the fermion generation puzzle based on a
nonabelian generalization of electric--magnetic duality derived some years ago.
This nonabelian duality implies the existence of another SU(3) symmetry dual to
colour, which is necessarily broken when colour is confined and so can play the
role of the ``horizontal'' symmetry for fermion generations. When thus
identified, dual colour then predicts 3 and only 3 fermion generations, besides
suggesting a special Higgs mechanism for breaking the generation symmetry. A
phenomenological model with a Higgs potential and a Yukawa coupling constructed
on these premises is shown to explain immediately all the salient qualitative
features of the fermion mass hierarchy and mixing pattern, excepting for the
moment CP-violation. Calculations already carried out to 1-loop order is shown
to give with only 3 adjustable parameters the following quantities all to
within present experimental error: all 9 CKM matrix elements for
quarks, the neutrino oscillation angles or the MNS lepton mixing matrix
elements , and the mass ratios . The special feature of this model crucial for deriving the above
results is a fermion mass matrix which changes its orientation (rotates) in
generation space with changing energy scale, a feature which is shown to have
direct empirical support.Comment: updated version of course of lectures given at the 42nd Cracow School
of Theoretical Physics, 2002, Polan
Modeling of secondary organic aerosol yields from laboratory chamber data
Laboratory chamber data serve as the basis for constraining models of secondary organic aerosol (SOA) formation. Current models fall into three categories: empirical two-product (Odum), product-specific, and volatility basis set. The product-specific and volatility basis set models are applied here to represent laboratory data on the ozonolysis of α-pinene under dry, dark, and low-NOx conditions in the presence of ammonium sulfate seed aerosol. Using five major identified products, the model is fit to the chamber data. From the optimal fitting, SOA oxygen-to-carbon (O/C) and hydrogen-to-carbon (H/C) ratios are modeled. The discrepancy between measured H/C ratios and those based on the oxidation products used in the model fitting suggests the potential importance of particle-phase reactions. Data fitting is also carried out using the volatility basis set, wherein oxidation products are parsed into volatility bins. The product-specific model is most likely hindered by lack of explicit inclusion of particle-phase accretion compounds. While prospects for identification of the majority of SOA products for major volatile organic compounds (VOCs) classes remain promising, for the near future empirical product or volatility basis set models remain the approaches of choice
Signal quality measures for unsupervised blood pressure measurement
Accurate systolic and diastolic pressure estimation, using automated blood pressure measurement, is difficult to achieve when the transduced signals are contaminated with noise or interference, such as movement artifact. This study presents an algorithm for automated signal quality assessment in blood pressure measurement by determining the feasibility of accurately detecting systolic and diastolic pressures when corrupted with various levels of movement artifact. The performance of the proposed algorithm is compared to a manually annotated reference scoring (RS). Based on visual representations and audible playback of Korotkoff sounds, the creation of the RS involved two experts identifying sections of the recorded sounds and annotating sections of noise contamination. The experts determined the systolic and diastolic pressure in 100 recorded Korotkoff sound recordings, using a simultaneous electrocardiograph as a reference signal. The recorded Korotkoff sounds were acquired from 25 healthy subjects (16 men and 9 women) with a total of four measurements per subject. Two of these measurements contained purposely induced noise artifact caused by subject movement. Morphological changes in the cuff pressure signal and the width of the Korotkoff pulse were extracted features which were believed to be correlated with the noise presence in the recorded Korotkoff sounds. Verification of reliable Korotkoff pulses was also performed using extracted features from the oscillometric waveform as recorded from the inflatable cuff. The time between an identified noise section and a verified Korotkoff pulse was the key feature used to determine the validity of possible systolic and diastolic pressures in noise contaminated Korotkoff sounds. The performance of the algorithm was assessed based on the ability to: verify if a signal was contaminated with any noise; the accuracy, sensitivity and specificity of this noise classification, and the systolic and diastolic pressure differences between the result obtained from the algorithm and the RS. 90% of the actual noise contaminated signals were correctly identified, and a sample-wise accuracy, sensitivity and specificity of 97.0%, 80.61% and 98.16%, respectively, were obtained from 100 pooled signals. The mean systolic and diastolic differences were 0.37 ± 3.31 and 3.10 ± 5.46 mmHg, respectively, when the artifact detection algorithm was utilized, with the algorithm correctly determined if the signal was clean enough to attempt an estimation of systolic or diastolic pressures in 93% of blood pressure measurements
Axiomatic Holonomy Maps and Generalized Yang-Mills Moduli Space
This article is a follow-up of ``Holonomy and Path Structures in General
Relativity and Yang-Mills Theory" by Barrett, J. W. (Int.J.Theor.Phys., vol.30,
No.9, 1991). Its main goal is to provide an alternative proof of this part of
the reconstruction theorem which concerns the existence of a connection. A
construction of connection 1-form is presented. The formula expressing the
local coefficients of connection in terms of the holonomy map is obtained as an
immediate consequence of that construction. Thus the derived formula coincides
with that used in "On Loop Space Formulation of Gauge Theories" by Chan, H.-M.,
Scharbach, P. and Tsou S.T. (Ann.Phys., vol.167, 454-472, 1986). The
reconstruction and representation theorems form a generalization of the fact
that the pointed configuration space of the classical Yang-Mills theory is
equivalent to the set of all holonomy maps. The point of this generalization is
that there is a one-to-one correspondence not only between the holonomy maps
and the orbits in the space of connections, but also between all maps from the
loop space on to group fulfilling some axioms and all possible
equivalence classes of bundles with connection, where the equivalence
relation is defined by bundle isomorphism in a natural way.Comment: amslatex, 7 pages, no figure
Energetic Components of Cooperative Protein Folding
A new lattice protein model with a four-helix bundle ground state is analyzed
by a parameter-space Monte Carlo histogram technique to evaluate the effects of
an extensive variety of model potentials on folding thermodynamics. Cooperative
helical formation and contact energies based on a 5-letter alphabet are found
to be insufficient to satisfy calorimetric and other experimental criteria for
two-state folding. Such proteinlike behaviors are predicted, however, by models
with polypeptide-like local conformational restrictions and
environment-dependent hydrogen bonding-like interactions.Comment: 11 pages, 4 postscripts figures, Phys. Rev. Lett. (in press
- …