Literature on triggers of childhood migraine is sparse. This study was carried out in 200 children (7–15 years) with migraine from a metropolitan city in Eastern India, both retrospectively and prospectively, with headache diaries to note the incidence of various triggers. In the retrospective study, triggers could be identified in 94% of subjects while in 100% of children in the prospective part of the study more than one trigger could be identified. Most migraine triggers identified were environmental (sun exposure, hot humid weather, smoke and noise) and stress related (school stress mostly). Quite often these operated concurrently to precipitate individual migraine attacks.

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We describe a noniterative method for recovering optical absorption coefficient distribution from the absorbed energy map reconstructed using simulated and noisy boundary pressure measurements. The source reconstruction problem is first solved for the absorbed energy map corresponding to single- and multiple-source illuminations from the side of the imaging plane. It is shown that the absorbed energy map and the absorption coefficient distribution, recovered from the single-source illumination with a large variation in photon flux distribution, have signal-to-noise ratios comparable to those of the reconstructed parameters from a more uniform photon density distribution corresponding to multiple-source illuminations. The absorbed energy map is input as absorption coefficient times photon flux in the time-independent diffusion equation (DE) governing photon transport to recover the photon flux in a single step. The recovered photon flux is used to compute the optical absorption coefficient distribution from the absorbed energy map. In the absence of experimental data, we obtain the boundary measurements through Monte Carlo simulations, and we attempt to address the possible limitations of the DE model in the overall reconstruction procedure.

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A state-based peridynamic formulation for linear elastic shells is presented. The emphasis is on introducing, possibly for the first time, a general surface based peridynamic model to represent the deformation characteristics of structures that have one physical dimension much smaller than the other two. A new notion of curved bonds is exploited to cater for force transfer between the peridynamic particles describing the shell. Starting with the three dimensional force and deformation states, appropriate surface based force, moment and several deformation states are arrived at. Upon application on the curved bonds, such states beget the necessary force and deformation vectors governing the motion of the shell. Correctness of our proposal on the peridynamic shell theory is numerically assessed against static deformation of spherical and cylindrical shells and flat plates.

A new implicit local linearization method termed as the locally transversal linearization (LTL) is developed in the present paper for a numeric-analytical integration of nonlinear dynamical systems under deterministic and/or stochastic excitations. The LTL procedure is developed in such a way that, at a chosen time-instant, the LTL solution manifold transversally intersects the nonlinear solution manifold at that particular point or cross-section in the state-space where the solution vector needs to be obtained. In general, construction of the LTL equation is non-unique and thus it is generally needed to substitute the conditionally linear LTL-based solution into the given nonlinear ordinary differential equation (ODE) at a specified time-instant to ensure a transversal intersection. In the present study, however, it is demonstrated that a transversal intersection at a given time-instant may as well be ensured by just choosing a few specific forms of the LTL equation, thereby eliminating the need for substitution. This new variant of LTL is particularly suitable for discretization of stochastic differential equations (SDEs) in that one simultaneously avoids dealing with formal derivatives of Wiener processes while satisfying the nonlinear SDE at discrete time-points. The stochastic LTL procedure is adaptable for obtaining strong pathwise solutions of a general nonlinear dynamical system with continuous (but not necessarily differentiable) vector fields under additive and/or multiplicative excitations. A specific advantage of the LTL method is that for a class of response regime, herein referred to as the phase-independent regime, it can obtain an accurate description of response irrespective of the choice of the time-step and without a propagation of local errors. Presently, the method has been numerically illustrated for strong solutions of the hardening Duffing oscillator under deterministic (sinusoidal) or additive stochastic (white noise) excitations or their combination. Limited numerical results on periodic solutions, chaos with or without noise and stochastic resonance are included in this study. The results presented are indicative of the sample path accuracy, consistency, stochastic numerical stability and a partial insensitivity to time-step sizes of the proposed method.

The present report provides a detailed head to head comparative study of migraine pain location at onset and during established headache between children and adults belonging to the same ethnic group. Migraine pain location in 200 children and adolescents had already been reported (Chakravarty et al. in Cephalalgia 27:1109–1114, 2007). The present report includes data collected simultaneously and in a similar fashion from 800 adult migraineurs. Significant differences have been noted in migraine pain location. Unilateral onset pain is common in adults, side locked and vertex onset pain unusual in children, holocranial onset pain much common in children and cervico-occipital onset pain much less common in children. There have been differences in evolution of migraine pain as well. During established headache unilateral pain was recorded in only a small proportion of children (10.5%) whereas it was noted in many adults’ subjects (40.5%). Such a detailed comparative study had not been made earlier.

A stable aqueous dispersion (5 mg ml −1) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55-60 mV were obtained indicating the high stability of aqueous graphene dispersions.