Plagiocephaly Perception and Prevention: A Need to Intervene Early to Educate Parents

Background: Plagiocephaly is a condition where the cranium has been malformed because of external forces or premature cranial suture fusion. This study’s objective was to gather and examine data regarding parent and caregiver awareness of plagiocephaly and its potential impact on development as well as to determine their rate of concern for positional flattening. Method: A cross-sectional survey study was conducted. Categorical variables were described by frequency and proportions. The study was conducted across eight outpatient pediatric sites. Approximately 1,100 parents and caregivers were targeted. Inclusion criteria required participants to be willing to answer the questionnaire, to be 18 years of age or older, and to have an infant 12 months of age or younger. Results: There were 404 participants, most of whom were female (89.8%) and 30–39 years of age (61.1%). Nineteen children (4.7%) were reported to have plagiocephaly, torticollis, and/or muscle weakness (PTM). A greater percentage of the participants with a child with PTM knew of positional flattening or plagiocephaly (73.3%) compared to those without (53.8%). The respondents with a child with PTM had a greater concern about plagiocephaly than those without (p = .03). Many of the respondents (65.3%) would use a device designed to prevent plagiocephaly. Conclusion: Many parents and caregivers were unaware of plagiocephaly and its potential impact on facial symmetry. A greater percentage of the participants with a child with PTM knew of positional flattening and also had a greater concern about plagiocephaly than those without

On Krein-like theorems for noncanonical Hamiltonian systems with continuous spectra: application to Vlasov-Poisson

The notions of spectral stability and the spectrum for the Vlasov-Poisson system linearized about homogeneous equilibria, f_0(v), are reviewed. Structural stability is reviewed and applied to perturbations of the linearized Vlasov operator through perturbations of f_0. We prove that for each f_0 there is an arbitrarily small delta f_0' in W^{1,1}(R) such that f_0+delta f_0$is unstable. When$f_0$ is perturbed by an area preserving rearrangement, f_0 will always be stable if the continuous spectrum is only of positive signature, where the signature of the continuous spectrum is defined as in previous work. If there is a signature change, then there is a rearrangement of f_0 that is unstable and arbitrarily close to f_0 with f_0' in W^{1,1}. This result is analogous to Krein's theorem for the continuous spectrum. We prove that if a discrete mode embedded in the continuous spectrum is surrounded by the opposite signature there is an infinitesimal perturbation in C^n norm that makes f_0 unstable. If f_0 is stable we prove that the signature of every discrete mode is the opposite of the continuum surrounding it.Comment: Submitted to the journal Transport Theory and Statistical Physics. 36 pages, 12 figure

Universality of Performance Indicators based on Citation and Reference Counts

We find evidence for the universality of two relative bibliometric indicators of the quality of individual scientific publications taken from different data sets. One of these is a new index that considers both citation and reference counts. We demonstrate this universality for relatively well cited publications from a single institute, grouped by year of publication and by faculty or by department. We show similar behaviour in publications submitted to the arXiv e-print archive, grouped by year of submission and by sub-archive. We also find that for reasonably well cited papers this distribution is well fitted by a lognormal with a variance of around 1.3 which is consistent with the results of Radicchi, Fortunato, and Castellano (2008). Our work demonstrates that comparisons can be made between publications from different disciplines and publication dates, regardless of their citation count and without expensive access to the whole world-wide citation graph. Further, it shows that averages of the logarithm of such relative bibliometric indices deal with the issue of long tails and avoid the need for statistics based on lengthy ranking procedures.Comment: 15 pages, 14 figures, 11 pages of supplementary material. Submitted to Scientometric

Characterization of the Interaction between the Cohesin Subunits Rad21 and SA1/2

The cohesin complex is responsible for the fidelity of chromosomal segregation during mitosis. It consists of four core subunits, namely Rad21/Mcd1/Scc1, Smc1, Smc3, and one of the yeast Scc3 orthologs SA1 or SA2. Sister chromatid cohesion is generated during DNA replication and maintained until the onset of anaphase. Among the many proposed models of the cohesin complex, the ﾒcoreﾒ cohesin subunits Smc1, Smc3, and Rad21 are almost universally displayed as tripartite ring. However, other than its supportive role in the cohesin ring, little is known about the fourth core subunit SA1/SA2. To gain deeper insight into the function of SA1/SA2 in the cohesin complex, we have mapped the interactive regions of SA2 and Rad21 in vitro and ex vivo. Whereas SA2 interacts with Rad21 through a broad region (301ﾖ750 aa), Rad21 binds to SA proteins through two SA-binding motifs on Rad21, namely N-terminal (NT) and middle part (MP) SA-binding motif, located At 60-81 aa of the N-terminus and 383ﾖ392 aa of the MP of Rad21, respectively. The MP SA-binding motif is a 10 amino acid, a-helical motif. Deletion of these 10 amino acids or mutation of three conserved amino acids (L385, F389, and T390) in this ahelical motif significantly hinders Rad21 from physically interacting with SA1/2. Besides the MP SA-binding motif, the NT SAbinding motif is also important for SA1/2 interaction. Although mutations on both SA-binding motifs disrupt Rad21-SA1/2 interaction, they had no apparent effect on the Smc1-Smc3-Rad21 interaction. However, the Rad21-Rad21 dimerization was reduced by the mutations, indicating potential involvement of the two SA-binding motifs in the formation of the two-ring handcuff for chromosomal cohesion. Furthermore, mutant Rad21 proteins failed to significantly rescue precocious chromosome separation caused by depletion of endogenous Rad21 in mitotic cells, further indicating the physiological significance of the two SA-binding motifs of Rad21

Initiator Elements Function to Determine the Activity State of BX-C Enhancers

A >300 kb cis-regulatory region is required for the proper expression of the three bithorax complex (BX-C) homeotic genes. Based on genetic and transgenic analysis, a model has been proposed in which the numerous BX-C cis-regulatory elements are spatially restricted through the activation or repression of parasegment-specific chromatin domains. Particular early embryonic enhancers, called initiators, have been proposed to control this complex process. Here, in order to better understand the process of domain activation, we have undertaken a systematic in situ dissection of the iab-6 cis-regulatory domain using a new method, called InSIRT. Using this method, we create and genetically characterize mutations affecting iab-6 function, including mutations specifically modifying the iab-6 initiator. Through our mutagenesis of the iab-6 initiator, we provide strong evidence that initiators function not to directly control homeotic gene expression but rather as domain control centers to determine the activity state of the enhancers and silencers within a cis-regulatory domain

Transparent Boundary Condition for Oseen-Frank Model. Application for NLC Cells With Patterned Electrodes

In the present work a novel application of Transparent Boundary Conditions (TBC) to nematic liquid crystal cells (NLCC) with planar alignment and a patterned electrode is studied. This device is attracting great interest since it allows soliton steering by optically and externally induced waveguides. We employ the continuum Oseen-Frank theory to find the tilt and twist angle distributions in the cell under the one-constant approximation. The electric field distribution takes into account the whole 2D permittivity tensor for the transverse coordinates. Standard finite difference time domain methods together with an iterative method is applied to find an approximate solution to our coupled problem. A novel class of TBC is used to correctly define the boundary for both the distortion angle problem and the electric field distribution when using patterned electrodes. Thus, we achieve an important decrease of computational needs when solving this kind of problems and we are also capable of exploring weak anchoring conditions for NLCC.Orquín Serrano, I.; Vijande, J.; Villatoro Machuca, FR.; Ferrando, A.; Fernández De Córdoba Castellá, PJ.; Michinel Alvarez, H. (2015). Transparent Boundary Condition for Oseen-Frank Model. Application for NLC Cells With Patterned Electrodes. Journal of Physics: Conference Series. 605:0120281-01202811. doi:10.1088/1742-6596/605/1/012028S012028101202811605Peccianti, M., De Rossi, A., Assanto, G., De Luca, A., Umeton, C., & Khoo, I. C. (2000). Electrically assisted self-confinement and waveguiding in planar nematic liquid crystal cells. Applied Physics Letters, 77(1), 7-9. doi:10.1063/1.126859Peccianti, M., & Assanto, G. (2001). Signal readdressing by steering of spatial solitons in bulk nematic liquid crystals. Optics Letters, 26(21), 1690. doi:10.1364/ol.26.001690Peccianti, M., Conti, C., Assanto, G., De Luca, A., & Umeton, C. (2002). All-optical switching and logic gating with spatial solitons in liquid crystals. Applied Physics Letters, 81(18), 3335-3337. doi:10.1063/1.1519101Fratalocchi, A., Assanto, G., Brzdąkiewicz, K. A., & Karpierz, M. A. (2005). All-optical switching and beam steering in tunable waveguide arrays. Applied Physics Letters, 86(5), 051112. doi:10.1063/1.1857071Fratalocchi, A., Assanto, G., Brzdąkiewicz, K. A., & Karpierz, M. A. (2005). Optical multiband vector breathers in tunable waveguide arrays. Optics Letters, 30(2), 174. doi:10.1364/ol.30.000174Beeckman, J., Neyts, K., & Haelterman, M. (2006). Patterned electrode steering of nematicons. Journal of Optics A: Pure and Applied Optics, 8(2), 214-220. doi:10.1088/1464-4258/8/2/018Peccianti, M., Dyadyusha, A., Kaczmarek, M., & Assanto, G. (2008). Escaping Solitons from a Trapping Potential. Physical Review Letters, 101(15). doi:10.1103/physrevlett.101.153902Kivshar, Y. (2006). Bending light at will. Nature Physics, 2(11), 729-730. doi:10.1038/nphys452Alexe-Ionescu, A. L., Barberi, R., Barbero, G., & Giocondo, M. (1994). Anchoring energy for nematic liquid crystals: Contribution from the spatial variation of the elastic constants. Physical Review E, 49(6), 5378-5388. doi:10.1103/physreve.49.5378Allen, M. P., & Frenkel, D. (1988). Calculation of liquid-crystal Frank constants by computer simulation. Physical Review A, 37(5), 1813-1816. doi:10.1103/physreva.37.1813He, S. (2001). Iterative finite-difference method for calculating the distribution of a liquid-crystal director. Optical Engineering, 40(11), 2552. doi:10.1117/1.1411974Engquist, B., & Majda, A. (1977). Absorbing boundary conditions for the numerical simulation of waves. Mathematics of Computation, 31(139), 629-629. doi:10.1090/s0025-5718-1977-0436612-4Grote, M. J., & Keller, J. B. (1995). Exact Nonreflecting Boundary Conditions for the Time Dependent Wave Equation. SIAM Journal on Applied Mathematics, 55(2), 280-297. doi:10.1137/s0036139993269266Hagstrom, T., Warburton, T., & Givoli, D. (2010). Radiation boundary conditions for time-dependent waves based on complete plane wave expansions. Journal of Computational and Applied Mathematics, 234(6), 1988-1995. doi:10.1016/j.cam.2009.08.050Baskakov, V. A., & Popov, A. V. (1991). Implementation of transparent boundaries for numerical solution of the Schrödinger equation. Wave Motion, 14(2), 123-128. doi:10.1016/0165-2125(91)90053-qLubich, C., & Schädle, A. (2002). Fast Convolution for Nonreflecting Boundary Conditions. SIAM Journal on Scientific Computing, 24(1), 161-182. doi:10.1137/s1064827501388741Kuska, J.-P. (1992). Absorbing boundary conditions for the Schrödinger equation on finite intervals. Physical Review B, 46(8), 5000-5003. doi:10.1103/physrevb.46.5000Di Menza, L. (1996). Absorbing boundary conditions on a hypersurface for the Schrödinger equation in a half-space. Applied Mathematics Letters, 9(4), 55-59. doi:10.1016/0893-9659(96)00051-1Schädle, A. (2002). Non-reflecting boundary conditions for the two-dimensional Schrödinger equation. Wave Motion, 35(2), 181-188. doi:10.1016/s0165-2125(01)00098-1Arnold, A., Ehrhardt, M., & Sofronov, I. (2003). Discrete transparent boundary conditions for the Schrödinger equation: fast calculation, approximation, and stability. Communications in Mathematical Sciences, 1(3), 501-556. doi:10.4310/cms.2003.v1.n3.a7Lindquist, J. M., Neta, B., & Giraldo, F. X. (2012). High-order non-reflecting boundary conditions for dispersive waves in polar coordinates using spectral elements. Applied Mathematics and Computation, 218(12), 6666-6676. doi:10.1016/j.amc.2011.12.023Sun, Z., Wu, X., Zhang, J., & Wang, D. (2012). A linearized difference scheme for semilinear parabolic equations with nonlinear absorbing boundary conditions. Applied Mathematics and Computation, 218(9), 5187-5201. doi:10.1016/j.amc.2011.10.083Hadley, G. R. (1991). Transparent boundary condition for beam propagation. Optics Letters, 16(9), 624. doi:10.1364/ol.16.000624Hadley, G. R. (1992). Transparent boundary condition for the beam propagation method. IEEE Journal of Quantum Electronics, 28(1), 363-370. doi:10.1109/3.119536Beeckman, J., Chałubinska, K., & Neyts, K. (2006). Lateral Light Propagation in SSFLC Devices and Thermal Optical Nonlinearities. Ferroelectrics, 344(1), 225-231. doi:10.1080/00150190600968348Peccianti, M., Dyadyusha, A., Kaczmarek, M., & Assanto, G. (2006). Tunable refraction and reflection of self-confined light beams. Nature Physics, 2(11), 737-742. doi:10.1038/nphys42

Criticality Analysis of Activity Networks under Interval Uncertainty

Dedicated to the memory of Professor Stefan Chanas - The extended abstract version of this paper has appeared in Proceedings of 11th International Conference on Principles and Practice of Constraint Programming (CP2005) ("Interval Analysis in Scheduling", Fortin et al. 2005)International audienceThis paper reconsiders the Project Evaluation and Review Technique (PERT) scheduling problem when information about task duration is incomplete. We model uncertainty on task durations by intervals. With this problem formulation, our goal is to assert possible and necessary criticality of the different tasks and to compute their possible earliest starting dates, latest starting dates, and floats. This paper combines various results and provides a complete solution to the problem. We present the complexity results of all considered subproblems and efficient algorithms to solve them

A bootstrap method for sum-of-poles approximations

A bootstrap method is presented for finding efficient sum-of-poles approximations of causal functions. The method is based on a recursive application of the nonlinear least squares optimization scheme developed in (Alpert et al. in SIAM J. Numer. Anal. 37:1138–1164, 2000), followed by the balanced truncation method for model reduction in computational control theory as a final optimization step. The method is expected to be useful for a fairly large class of causal functions encountered in engineering and applied physics. The performance of the method and its application to computational physics are illustrated via several numerical examples

The Caravan Rolls On

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68409/2/10.1177_107554707900100103.pd