The ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ system with $0.2\ensuremath{\lesssim}x\ensuremath{\lesssim}0.4$ has traditionally been modeled a ``double-exchange'' Hamiltonian in which it is assumed that the only relevant physics tendency of carrier hopping to line up neighboring spins. We present solution double-exchange model, show incompatible many aspects data, and propose addition strong electron-phonon interaction arising from Jahn-Teller splitting outer Mn...

A model for the doped rare-earth manganites such as ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ incorporating physics of dynamic Jahn-Teller and double-exchange effects is presented solved via a dynamical mean field approximation. The interplay these two electron phonon coupling varied reproduces observed behavior resistivity magnetic transition temperature.

This review is an expository treatment of the displacement one fluid by another in a two-dimensional geometry (a Hele-Shaw cell). The Saffman-Taylor equations modeling this system are discussed. They simulated random-walk techniques and studied methods from complex analysis. stability generated patterns (fingers) WKB approximation analytic techniques. primary conclusions reached that (a) fingers linearly stable even at highest velocities, (b) they nonlinearly unstable against noise or...

Regulation of cell growth and proliferation has a fundamental role in animal plant development the progression cancer. In context development, it is important to understand mechanisms that coordinate patterning tissues. Imaginal discs, which are larval precursors fly limbs organs, have provided much what we currently know about these processes. Here, consider mechanism responsible for observed uniformity wing imaginal persists presence gradients inducing morphogens spite stochastic nature...

We show that the Anomalous Hall Effect (AHE) observed in Colossal Magnetoresistance Manganites is a manifestation of Berry phase effects caused by carrier hopping non-trivial spin background. determine magnitude and temperature dependence contribution to AHE, finding it increases rapidly as raised from zero through magnetic transition T_c, peaks at $T_{max} > T_c$ decays power T, agreement with experimental data. suggest our theory may be relevant anomalous hall effect conventional ferromagnets well.

A basic challenge in systems biology is to understand the dynamical behavior of gene regulation networks. Current approaches aim at determining network structure based on genomic-scale data. However, connectivity alone not sufficient define its dynamics; one needs also specify kinetic parameters for reactions. Here, we ask whether effective can be assigned a transcriptional expression We present combined experimental and theoretical approach accurate high temporal-resolution measurement...

The heat flux (Nusselt number) as a function of Rayleigh number, ${\mathit{N}}_{\mathrm{Nu}}$\ensuremath{\approxeq}0.3${\mathit{N}}_{\mathrm{Ra}}^{2/7}$, is deduced from the presence mean flow and nesting thermal boundary layer within viscous one. numerical coefficients are obtained those known empirically for turbulent layers. consistency our assumptions Prandtl number limits this regime to...

Control of cell proliferation is a fundamental aspect tissue physiology central to morphogenesis, wound healing, and cancer. Although many the molecular genetic factors are now known, system level regulation growth still poorly understood. A simple form inhibition encountered in vitro normally differentiating epithelial cultures known as “contact inhibition.” The study presented here provides quantitative characterization contact dynamics on tissue-wide single levels. Using long-term...

The ground state of a quantum vacancy in 2D antiferromagnet is found to involve long-range dipolar distortion the staggered magnetization. An effective Hamiltonian vacancies interacting with long-wavelength spin waves derived. implications for anitferromagnetic order are discussed.

A low density of vacancies in a 2D, spin-(1/2, Heisenberg antiferromagnet leads (for range effective couplings) to metallic phase with incommensurate antiferromagnetic order, i.e., the staggered magnetization rotating plane wave number proportional density. This structure originates from polarization dipole moments vacancies. The excitation spectrum this spiral state includes an interesting low-lying mode. Implications for neutron scattering and normal-state resistivity are discussed.

A fundamental and unresolved problem in animal development is the question of how a growing tissue knows when it has achieved its correct final size. widely held view suggests that this process controlled by morphogen gradients, which adapt to size become flatter as grows, leading eventually growth arrest. Here, we present evidence decapentaplegic (Dpp) distribution developing Drosophila wing imaginal disk does not We measure functional Dpp-GFP transgene Dpp signal transduced phospho-Mad...

Human seasonal influenza viruses evolve rapidly, enabling the virus population to evade immunity and reinfect previously infected individuals. Antigenic properties are largely determined by surface glycoprotein hemagglutinin (HA), amino acid substitutions at exposed epitope sites in HA mediate loss of recognition antibodies. Here, we show that antigenic differences measured through serological assay data well described a sum changes along path connecting phylogenetic tree. This mapping onto...

Given a sample of genome sequences from an asexual population, can one predict its evolutionary future? Here we demonstrate that the branching patterns reconstructed genealogical trees contains information about relative fitness sampled and this be used to successful strains. Our approach is based on assumption evolution proceeds by accumulation small effect mutations, does not require species specific input applied any population under persistent selection pressure. We performance using...

During embryogenesis tissue layers undergo morphogenetic flow rearranging and folding into specific shapes. While developmental biology has identified key genes local cellular processes, global coordination of remodeling at the organ scale remains unclear. Here, we combine in toto light-sheet microscopy Drosophila embryo with quantitative analysis physical modeling to relate patterns force generation during gastrulation process. We find that complex spatio-temporal pattern can be predicted...

We use the dynamical mean-field method to study a model of electrons Jahn-Teller coupled localized classical oscillators and ferromagnetically ``core spins.'' The model, we argue, contains essential physics ``colossal magnetoresistance'' manganites ${\mathrm{Re}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{A}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$. determine different regimes present results for temperature frequency dependence conductivity, electron spectral function, root-mean-square...

The energy of one and two holes in a Hubbard antiferromagnet for nonzero exchange, J, the Ising limit is calculated within Brinkman-Rice approximation. Only p- d-symmetry states bind with an order J. implications superconductivity antiferromagnetism doped insulators discussed.

A model of many globally coupled phase oscillators is studied by analytical and numerical methods. Each oscillator to all the other via a global driving force that takes form ${\mathit{tsum}}_{\mathit{j}}$ g(${\mathrm{\ensuremath{\varphi}}}_{\mathit{j}}$), where g(${\mathrm{\ensuremath{\varphi}}}_{\mathit{j}}$) periodic function jth phase. The spatiotemporal properties attractors in various regions parameter space are analyzed. In addition simple spatially uniform fixed points limit cycles,...

We present a theory of Raman scattering in the Hubbard model. The light has two contributions. One gives rise to by spin degrees freedom insulating case where general form Hamiltonian is derived. fluctuations ``chiral'' operator ${\mathrm{\ensuremath{\Sigma}}}_{{\mathit{S}}_{\mathit{i}}}$\ensuremath{\cdot}(${\mathrm{S}}_{\mathit{i}}$\ifmmode\times\else\texttimes\fi{}${\mathrm{S}}_{\mathit{k}}$) are shown contribute ${\mathit{B}}_{2\mathit{g}}$ geometry. other contributes doped and probe...