20,925 research outputs found
Thermal fluctuations and anomalous elasticity of homogeneous nematic elastomers
We present a unified formulation of a rotationally invariant nonlinear
elasticity for a variety of spontaneously anisotropic phases, and use it to
study thermal fluctuations in nematic elastomers and spontaneously anisotropic
gels. We find that in a thermodynamic limit homogeneous nematic elastomers are
universally incompressible, are characterized by a universal ratio of shear
moduli, and exhibit an anomalous elasticity controlled by a nontrivial low
temperature fixed point perturbative in D=3-epsilon dimensions. In three
dimensions, we make predictions that are asymptotically exact.Comment: 4 RevTeX pgs,,submitted to Europhysics Letter
Quality Indicators Guiding Secondary Career and Technical Education Programs of Study
The purpose of this study was to examine quality indicators currently guiding the rigor of secondary career and technical education (CTE) programs of study in the United States. Quality indicators are desirable characteristics or expectations for a comprehensive and effective CTE program of study. As of May 2017, we were able to locate publicly accessible secondary CTE quality program standards/guidelines for 38 states. A majority (n=24) updated their secondary CTE quality program standards/guidelines within the last five years (i.e., 2012-2017). Deductive content analysis was conducted to examine the 38 state profiles using the Association of Career and Technical Education (ACTE) Quality CTE Program of Study Framework 4.0 for coding purposes. Common quality elements and key quality indicators were identified from those state documents, which supplements the ACTE Framework. Implications and examples for practice are also discussed
A non-equilibrium dynamic mechanism for the allosteric effect
Allosteric regulation is often viewed as thermodynamic in nature. However
protein internal motions during an enzymatic reaction cycle can be slow hopping
processes over numerous potential barriers. We propose that regulating
molecules may function by modifying the nonequilibrium protein dynamics. The
theory predicts that an enzyme under the new mechanism has different
temperature dependence, waiting time distribution of the turnover cycle, and
dynamic fluctuation patterns with and without effector. Experimental tests of
the theory are proposed.Comment: accepted by Phys. Rev. Lett. Major revisions were made to fit the
style. 4 pages, 2 figure
Generalized Friedberg-Lee model for neutrino masses and leptonic CP violation from mu-tau symmetry breaking
Assuming the Majorana nature of massive neutrinos, we generalize the
Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass
matrix M_\nu. The most general case with all the free parameters of M_\nu being
complex is discussed. We show that a favorable neutrino mixing pattern (with
\theta_12 \approx 35.3^\circ, \theta_23=45^\circ, \theta_13 \neq 0^\circ and
\delta=90^\circ) can naturally be derived from M_\nu, if it has an approximate
or softly-broken \mu-\tau symmetry. We also point out a different way to obtain
the nearly tri-bimaximal neutrino mixing pattern with \delta=0^\circ and
non-vanishing Majorana phases.Comment: 4 pages. Talk given by He Zhang at the 4th International Conference
on Flavor Physics, 24-28 September 2007, Beijing (to appear in the
proceedings
Can CPT Symmetry Be Tested With K^0 vs \bar{K}^0--> \pi^+\pi^-\pi^0 Decays?
We show that the CP-violating effect in K^0 vs \bar K^0-->\pi^+\pi^-\pi^0
decays differs from that in K_{\rm L}-->\pi^+\pi^-, K_{\rm L}-->\pi^0\pi^0 or
the semileptonic K_{\rm L} transitions, if there exists CPT violation in
K^0-\bar{K}^0 mixing. A delicate measurement of this difference in the KTeV
experiment and at the \phi factory will provide a new test of CPT symmetry in
the neutral kaon system.Comment: RevTex 6 pages. Phys. Rev. D (in printing
Distinguishable RGE running effects between Dirac neutrinos and Majorana neutrinos with vanishing Majorana CP-violating phases
In a novel parametrization of neutrino mixing and in the approximation of
-lepton dominance, we show that the one-loop renormalization-group
equations (RGEs) of Dirac neutrinos are different from those of Majorana
neutrinos even if two Majorana CP-violating phases vanish. As the latter can
keep vanishing from the electroweak scale to the typical seesaw scale, it makes
sense to distinguish between the RGE running effects of neutrino mixing
parameters in Dirac and Majorana cases. The differences are found to be quite
large in the minimal supersymmetric standard model with sizable ,
provided the masses of three neutrinos are nearly degenerate or have an
inverted hierarchy.Comment: 12 pages, 5 figure
- …