Computing a rectilinear shortest path amid splinegons in plane

We reduce the problem of computing a rectilinear shortest path between two given points s and t in the splinegonal domain \calS to the problem of computing a rectilinear shortest path between two points in the polygonal domain. As part of this, we define a polygonal domain \calP from \calS and transform a rectilinear shortest path computed in \calP to a path between s and t amid splinegon obstacles in \calS. When \calS comprises of h pairwise disjoint splinegons with a total of n vertices, excluding the time to compute a rectilinear shortest path amid polygons in \calP, our reduction algorithm takes O(n + h \lg{n}) time. For the special case of \calS comprising of concave-in splinegons, we have devised another algorithm in which the reduction procedure does not rely on the structures used in the algorithm to compute a rectilinear shortest path in polygonal domain. As part of these, we have characterized few of the properties of rectilinear shortest paths amid splinegons which could be of independent interest

Lignosulfonate as a Strength Additive for Non-Wood Paperboard

Recycle mills that use old corrugated cardboard (OCC) in their furnish experience difficulties in maintaining the quality of the paperboard produced. Recycle mills using the OCC collect their OCC from many parts of the world. Countries such as China and Japan use rice fibers in the production of corrugated cardboard. Other countries use straw as a fiber source. The end result is that OCC in the United States contains a portion of non-wood fibers as well as the typical wood fibers. Paperboard containing these non-wood fibers typically has lower strength properties than paperboard produced from pure wood fibers. Literature suggests that lignosulfonate compounds can be used as a strength agent for recycled wood fiber paperboards. Calcium lignosulfonate is readily available and is not costly and would prove to be an ideal strength agent for use in recycled paperboard. The objective of this project was to test calcium lignosulfonate as a strength agent in improving the runnability and strength properties on paperboard made from wheat straw paperboard and/or paperboard containing a mixture of wheat straw and wood fibers. Handsheets (120g/m2 ) were prepared on a Noble and Wood handsheet machine. The handsheets from each furnish were then immersed in a bath of calcium lignosulfonate followed by an immersion in kymene. Calcium lignosulfonate levels were varied in the bath in order to control the amount of calcium lignosulfonate applied to each handsheet. The results show that as far as recycled pulp is concerned, CaLS at 10% is definitely beneficial compared with no CaLS in all strength properties. In the case of straw paperboard, 10% CaLS definitely gives higher strength properties compared with no CaLS (except for burst and Scott bond). Higher CaLS levels (10% or 20%) may be justified only in the case of ring crush. As for mixed fiber paperboard, CaLS seems to yield better strength properties (except in the case of Scott bond and burst). While 10% CaLS still seems to be sufficient, 20% seems to result in better crushing resistance and stiffness. The conclusion of this project is that 10% CaLS yields better strength properties in most of the cases and can be the starting point for further refinement studies

Histologie des formations embryogènes obtenues au cours de la culture in vitro du palmier à huile Elaeis guineensis Jacq

L'analyse histologique a été particulièrement centrée sur la formation et l'évolution des cellules et des nodules embryogènes au cours de la multiplication végétative in vitro du palmier à huile. Les cals primaires isolés des explants prolifèrent sur un milieu contenant du 2-4 D, des cytokinines et du charbon actif. Lorsque les conditions de culture sont favorables, la zone pseudo-cambiale qui assure la prolifération des cals nodulaires devient embryogène. Cette modification histologique est décrite. Des cellules embryogènes s'isolent, spécialement à la périphérie des cals, elles subissent un ou deux recloisonnements internes, mais les proembryons ainsi formés n'évoluent pas ultérieurement. L'arrêt de ce processus d'origine unicellulaire est discuté. L'évolution des cals se fait à partir des nombreux foyers méristématiques qui s'y forment. Ces foyers sont constitués par des cellules très actives possédant des caractères spéciaux qui sont décrits. Suite à l'activité de ces foyers, des petits nodules blanchâtres émergent. Ils s'isolent en formant un épiderme, se polarisent et donnent naissance à des embryons somatiques. A ce stade, ils sont transférés sur un milieu sans hormones de croissance sur lequel se déroule une embryogenèse adventive. Le processus d'embryogenèse somatique du palmier à huile, d'origine multicellulaire, est comparé avec celui décrit au niveau histologique pour d'autres palmacée

Suffix conjugates for a class of morphic subshifts

Let A be a finite alphabet and f: A^* --> A^* be a morphism with an iterative fixed point f^\omega(\alpha), where \alpha{} is in A. Consider the subshift (X, T), where X is the shift orbit closure of f^\omega(\alpha) and T: X --> X is the shift map. Let S be a finite alphabet that is in bijective correspondence via a mapping c with the set of nonempty suffixes of the images f(a) for a in A. Let calS be a subset S^N be the set of infinite words s = (s_n)_{n\geq 0} such that \pi(s):= c(s_0)f(c(s_1)) f^2(c(s_2))... is in X. We show that if f is primitive and f(A) is a suffix code, then there exists a mapping H: calS --> calS such that (calS, H) is a topological dynamical system and \pi: (calS, H) --> (X, T) is a conjugacy; we call (calS, H) the suffix conjugate of (X, T). In the special case when f is the Fibonacci or the Thue-Morse morphism, we show that the subshift (calS, T) is sofic, that is, the language of calS is regular

Quantum spin systems at positive temperature

We develop a novel approach to phase transitions in quantum spin models based on a relation to their classical counterparts. Explicitly, we show that whenever chessboard estimates can be used to prove a phase transition in the classical model, the corresponding quantum model will have a similar phase transition, provided the inverse temperature $\beta$ and the magnitude of the quantum spins \CalS satisfy \beta\ll\sqrt\CalS. From the quantum system we require that it is reflection positive and that it has a meaningful classical limit; the core technical estimate may be described as an extension of the Berezin-Lieb inequalities down to the level of matrix elements. The general theory is applied to prove phase transitions in various quantum spin systems with \CalS\gg1. The most notable examples are the quantum orbital-compass model on $\Z^2$ and the quantum 120-degree model on $\Z^3$ which are shown to exhibit symmetry breaking at low-temperatures despite the infinite degeneracy of their (classical) ground state.Comment: 47 pages, version to appear in CMP (style files included

Suffix conjugates for a class of morphic subshifts

Let A be a finite alphabet and f: A^* --> A^* be a morphism with an iterative fixed point f^\omega(\alpha), where \alpha{} is in A. Consider the subshift (X, T), where X is the shift orbit closure of f^\omega(\alpha) and T: X --> X is the shift map. Let S be a finite alphabet that is in bijective correspondence via a mapping c with the set of nonempty suffixes of the images f(a) for a in A. Let calS be a subset S^N be the set of infinite words s = (s_n)_{n\geq 0} such that \pi(s):= c(s_0)f(c(s_1)) f^2(c(s_2))... is in X. We show that if f is primitive and f(A) is a suffix code, then there exists a mapping H: calS --> calS such that (calS, H) is a topological dynamical system and \pi: (calS, H) --> (X, T) is a conjugacy; we call (calS, H) the suffix conjugate of (X, T). In the special case when f is the Fibonacci or the Thue-Morse morphism, we show that the subshift (calS, T) is sofic, that is, the language of calS is regular.https://www.cambridge.org/core/journals/ergodic-theory-and-dynamical-systems/article/suffix-conjugates-for-a-class-of-morphic-subshifts/A531E7B26F382EDAF8455382C9C1DC9

Measurement Errors and their Propagation in the Registration of Remote Sensing Images (?)

Reference control points (RCPs) used in establishing the regression model in the registration or geometric correction of remote sensing images are generally assumed to be ?perfect?. That is, the RCPs, as explanatory variables in the regression equation, are accurate and the coordinates of their locations have no errors. Thus ordinary least squares (OLS) estimator has been applied extensively to the registration or geometric correction of remotely sensed data. However, this assumption is often invalid in practice because RCPs always contain errors. Moreover, the errors are actually one of the main sources which lower the accuracy of geometric correction of an uncorrected image. Under this situation, the OLS estimator is biased. It cannot handle explanatory variables with errors and cannot propagate appropriately errors from the RCPs to the corrected image. Therefore, it is essential to develop new feasible methods to overcome such a problem. In this paper, we introduce the consistent adjusted least squares (CALS) estimator and propose a relaxed consistent adjusted least squares (RCALS) method, with the latter being more general and flexible, for geometric correction or registration. These estimators have good capability in correcting errors contained in the RCPs, and in propagating appropriately errors of the RCPs to the corrected image with and without prior information. The objective of the CALS and our proposed RCALS estimators is to improve the accuracy of measurement value by weakening the measurement errors. The validity of the CALS and RCALS estimators are first demonstrated by applying them to perform geometric corrections of controlled simulated images. The conceptual arguments are further substantiated by a real-life example. Compared to the OLS estimator, the CALS and RCALS estimators give a superior overall performances in estimating the regression coefficients and variance of measurement errors. Keywords: error propagation, geometric correction, ordinary least squares, registration, relaxed consistent adjusted least squares, remote sensing images.

Néoformation de jeunes plantes d'Elaeis guineensis à partir de cals primaires obtenus sur fragments foliaires cultivés in vitro

Une méthode rapide de multiplication végétative du palmier à huile a été obtenue par la voie d'une embryogenèse somatique sur cals primaires. Ces cals sont obtenus à partir de tissus foliaires, dans un délai de 2 à 3 mois après la mise en culture. Les embryoïdes apparaissent sur cals isolés environ 2 mois après leur isolement et leur repiquage en conditions "organogènes