Nonreciprocity as a generic route to traveling states

We examine a non-reciprocally coupled dynamical model of a mixture of two diffusing species. We demonstrate that nonreciprocity, which is encoded in the model via antagonistic cross diffusivities, provides a generic mechanism for the emergence of traveling patterns in purely diffusive systems with conservative dynamics. In the absence of non-reciprocity, the binary fluid mixture undergoes a phase transition from a homogeneous mixed state to a demixed state with spatially separated regions rich in one of the two components. Above a critical value of the parameter tuning non-reciprocity, the static demixed pattern acquires a finite velocity, resulting in a state that breaks both spatial and time translational symmetry, as well as the reflection parity of the static pattern. We elucidate the generic nature of the transition to traveling patterns using a minimal model that can be studied analytically. Our work has direct relevance to nonequilibrium assembly in mixtures of chemically interacting colloids that are known to exhibit non-reciprocal effective interactions, as well as to mixtures of active and passive agents where traveling states of the type predicted here have been observed in simulations. It also provides insight on transitions to traveling and oscillatory states seen in a broad range of nonreciprocal systems with non-conservative dynamics, from reaction-diffusion and prey-predators models to multispecies mixtures of microorganisms with antagonistic interactions.Comment: 8 pages, 3 figure

Enhanced diffusion and ordering of self-propelled rods

Starting from a minimal physical model of self propelled hard rods on a substrate in two dimensions, we derive a modified Smoluchowski equation for the system. Self -propulsion enhances longitudinal diffusion and modifies the mean field excluded volume interaction. From the Smoluchowski equation we obtain hydrodynamic equations for rod concentration, polarization and nematic order parameter. New results at large scales are a lowering of the density of the isotropic-nematic transition and a strong enhancement of boundary effects in confined self-propelled systems.Comment: 4 pages, 2 figure

Exogenous vs. Endogenous Consumer Preferences and Knowledge about Nutrition

Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

Constraints on First-Light Ionizing Sources from Optical Depth of the Cosmic Microwave Background

We examine the constraints on high-redshift star formation, ultraviolet and X-ray pre-ionization, and the epoch of reionization at redshift z_r, inferred from the recent WMAP-5 measurement, tau_e = 0.084 +/- 0.016, of the electron scattering optical depth of the cosmic microwave background (CMB). Half of this scattering can be accounted for by the optical depth, tau_e = 0.04-0.05, of a fully ionized intergalactic medium (IGM) at z < z_GP = 6-7, consistent with Gunn-Peterson absorption in neutral hydrogen. The required additional optical depth, Delta-tau_e = 0.03 +/- 0.02 at z > z_GP, constrains the ionizing contributions of first light sources. WMAP-5 also measured a significant increase in small-scale power, which lowers the required efficiency of star formation and ionization from mini-halos. Early massive stars (UV radiation) and black holes (X-rays) can produce a partially ionized IGM, adding to the residual electrons left from incomplete recombination. Inaccuracies in computing the ionization history, x_e(z), and degeneracies in cosmological parameters (Omega_m, Omega_b, sigma_8, n_s) add systematic uncertainty to the measurement and modeling of $\tau_e$. From the additional optical depth from sources at z > z_GP, we limit the star-formation efficiency, the rate of ionizing photon production for Pop III and Pop II stars, and the photon escape fraction, using standard histories of baryon collapse, minihalo star formation, and black-hole X-ray preionization.Comment: Greatly revised version, based on WMAP-5 results and new models. Accepted for ApJ (2008

A Prospective study to compare T2 Weighted MRI to CT imaging in volume delineation for radiotherapy planning in carcinoma cervix

OBJECTIVES: To compare magnetic resonance imaging (MRI), computed tomography (CT), and clinical examination to evaluate the impact of MRI on target volume delineation as compared to the volumes obtained on a CT scan and also to see the effect on staging and prognosis. METHODS: Twenty patients diagnosed with locally advanced carcinoma cervix underwent planning CT abdomen and pelvis which was fused with T2 weighted MRI images to evaluate the impact of MRI on target volume delineaton , to see if CT scan along with clinical findings can be a good alternate to MRI scan.A descriptive analysis and frequency distribution of the patient characteristics was done. Fisher's exact test was done to find out relationship between prognostic factors and image findings. PABAK was done to compare different imaging modalities (CT versus MRI).Paired T test was used for tumor volume comparison. RESULTS: MRI was better in tumor delineation as compared to CT scan. Additional imaging gave information regarding local extent of the disease, nodal involvement . Upstaging of disease helped in selecting appropriate treatment modality. CONCLUSION: Though the findings on CT, MRI, or PET examinations are not mandatory for FIGO staging it could be of additional benefit and provide extra information that would result in stage migration, help appropriate selection of treatment modality,result in more accurate radiotherapy treatment planning and also provide prognostic information that would impact on the outcome of treatment and survival. CT with good clinical examination could be used as an alternate to MRI where MRI is not feasible

Knowledge, Attitude and Awareness Among Dental Practitioners on Herpetic Neuritis

Herpetic neuritis is a painful condition that affects the nerve fibers and skin. It is a complication of shingles.It is the reemergence of the varicella zoster virus, or chickenpox virus, which has been dormant in the sensory dorsal root ganglia of the nervous system since childhood infection. These viral infections which occur in the oral mucosa are frequently encountered in general practice. The clinical diagnosis of these lesions can sometimes be confusing due to their similar clinical presentations. Therefore the main aim of this study is to determine the knowledge,awareness and management practices of herpetic neuritis in a dental clinical setup among dental practitioners.To analyse the awareness of herpetic neuritis among dental practitioners. This study was conducted as an online survey based on the awareness of herpetic neuritis among dental practitioners with the help of a survey planet . A Total of 100 dental practitioners were randomly enrolled in the study and voluntarily completed a questionnaire consisting of 10 close – ended questions data was collected and analysed. The results were demonstrated in the form of pie charts. About 96% of the participants were aware about the various diagnostic aids and management practices of herpetic neuritis patients and they have an overview upon the ways to implement them in their clinical practice. The knowledge and awareness among dentists about herpetic neuritis patients in a clinical setup is adequate and some of dentists had a negative attitude towards the management practices.Saveetha Dental College and Hospital