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Orientation Behavior (orientation + behavior)

Distribution by Scientific Domains
Polymers and Materials Science57%

Selected Abstracts

Mechanistic Investigation into the Unique Orientation Textures of Poly(vinylidene fluoride) in Blends with Nylon 11

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 10 2003
Yongjin Li
Abstract Self-seeded crystallization experiments were carried out to detect the mechanism of the unique orientation behavior of poly(vinylidene fluoride) (PVDF) in oriented PVDF/nylon 11 blends. It was found that primary nuclei have no effects on the final orientation textures adopted by PVDF. The results show that the PVDF crystal orientation in the oriented blends is determined in the early stage of crystal growth, thus a trans crystallization mechanism is preferred. Isothermal crystallization kinetics for the self-seeded and non-self-seeded crystallization at 145,°C. [source]

Employee motivation, external orientation and the technical efficiency of foreign-financed firms in China: a stochastic frontier analysis

MANAGERIAL AND DECISION ECONOMICS, Issue 3 2005
Vincent Mok
By using a stochastic frontier model, we have identified several firm-specific attributes as determinants of technical efficiency in foreign-financed manufacturing firms in southern China. The empirical results suggest a strong association between efficiency and employee motivation, which includes the use of bonus incentives and flexibility in employment policy. In terms of the external orientation behavior of firms, the findings do not support the export/efficiency relationship. Sample firms with a high degree of export-orientedness were less efficient, possibly due to the high transaction costs in China of exportation. As for the effects of expatriate input on production, our empirical evidence revealed that firms with a relatively high expatriate ratio performed less efficiently than others did. These two findings may have significant implications for the marketing strategies and management (including the localization) of human resources of foreign-financed firms in China. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Crystal structure and orientation behavior of transversely compressed poly(ethylene- co -1-octene) filaments

POLYMER ENGINEERING & SCIENCE, Issue 12 2008
Haifeng Shan
A basic study on crystal structure and orientation behavior of transversely compressed ethylene-1-octene copolymer with different 1-octene contents was described. All polymers were first melt spun under different spinline stress and subsequently transversely compressed. For the melt-spun filaments, an orthorhombic crystal structure was found for all polymers, but a pseudo-hexagonal mesophase was also found for polymers with the highest 1-octene level (13.3 mol%). For the transversely compressed filaments, several reflection peaks from a monoclinic unit cell were found for polyethylene without octene. For those with higher octene levels, the reflection peaks from monoclinic became fainter and disappeared for the one with the highest 1-octene level. After being transversely compressed, the (110) and (200) peaks of orthorhombic crystal structures became oriented along the meridian direction, which is the fiber axis direction. The reason for this appears to be that the compression deformation of the filament induces elongation along its width direction and shrinkage along its length and thickness direction, and in this change the polymer chain orients. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source]

Molecular orientation, crystallinity, and flexural modulus correlations in injection molded polypropylene/talc composites

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2010
Marcia Cristina Branciforti
Abstract In order to promote better understanding of the structure-mechanical properties relationships of filled thermoplastic compounds, the molecular orientation and the degree of crystallinity of injection molded talc-filled isotactic polypropylene (PP) composites were investigated by X-ray pole figures and wide-angle X-ray diffraction (WAXD). The usual orientation of the filler particles, where the plate planes of talc particles are oriented parallel to the surface of injection molding and influence the orientation of the , -PP crystallites was observed. The PP crystallites show bimodal orientation in which the c - and a*-axes are mixed oriented to the longitudinal direction (LD) and the b -axis is oriented to the normal direction (ND). It was found that the preferential b -axis orientation of PP crystallites increases significantly in the presence of talc particles up to 20,wt% in the composites and then levels-off at higher filler content. WAXD measurements of the degree of crystallinity through the thickness of injection molded PP/talc composites indicated an increasing gradient of PP matrix crystallinity content from the core to the skin layers of the molded plaques. Also, the bulk PP crystallinity content of the composites, as determined by DSC measurements, increased with talc filler concentration. The bulk crystallinity content of PP matrix and the orientation behavior of the matrix PP crystallites and that of the talc particles in composites are influenced by the presence of the filler content and these three composite's microstructure modification factors influence significantly the flexural moduli and the mechanical stiffness anisotropy data (ELD/ETD) of the analyzed PP/talc composites. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Rat anterodorsal thalamic head direction neurons depend upon dynamic visual signals to select anchoring landmark cues

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2004
Michaėl B. Zugaro
Abstract Head direction cells, which are functionally coupled to ,place' cells of the hippocampus, a structure critically involved in spatial cognition, are likely neural substrates for the sense of direction. Here we studied the mechanism by which head direction cells are principally anchored to background visual cues [M.B. Zugaro et al. (2001) J. Neurosci., 21, RC154,1,5]. Anterodorsal thalamic head direction cells were recorded while the rat foraged on a small elevated platform in a 3-m diameter cylindrical enclosure. A large card was placed in the background, near the curtain, and a smaller card was placed in the foreground, near the platform. The cards were identically marked, proportionally dimensioned, subtended the same visual angles from the central vantage point and separated by 90°. The rat was then disoriented in darkness, the cards were rotated by 90° in opposite directions about the center and the rat was returned. Preferred directions followed either the background card, foreground card or midpoint between the two cards. In continuous lighting, preferred directions shifted to follow the background cue in most cases (30 of the 53 experiments, Batschelet V -test, P < 0.01). Stroboscopic illumination, which perturbs dynamic visual signals (e.g. motion parallax), blocked this selectivity. Head direction cells remained equally anchored to the background card, foreground card or configuration of the two cards (Watson test, P > 0.1). This shows that dynamic visual signals are critical in distinguishing typically more stable background cues which govern spatial neuronal responses and orientation behaviors. [source]

Six-week postpartum maternal depressive symptoms and 4-month mother,infant self- and interactive contingency,

INFANT MENTAL HEALTH JOURNAL, Issue 5 2008
Beatrice Beebe
Associations of 6-week maternal depressive symptoms [Center for Epidemiological Studies Depression Scale (CES-D)] with 4-month mother,infant self- and interactive contingency patterns during face-to-face play were investigated in 132 dyads. Self- and interactive contingency (auto- and lagged cross-correlation, respectively) were assessed by multilevel time-series analysis. Infant and mother gaze, facial and vocal affect, touch, and spatial orientation behaviors were coded second-by-second from split-screen videotape, and a multimodal measure of facial,visual "engagement" was constructed, generating nine modality pairings. With higher CES-D, the self-contingency of both partners was lowered in most modalities. With higher CES-D, interactive contingency values were both heightened (in some modalities) and lowered (in others), varying by partner. These results are consistent with an optimal midrange model. With higher CES-D, interactive contingency showed the following patterns: (a) Mothers and their infants had a reciprocal orientational sensitivity; (b) mothers and infants manifested a reciprocal intermodal discordance in attention versus affect coordination, lowering gaze coordination, but heightening affective coordination; (c) infants heightened, but mothers lowered, touch coordination with partner touch,an "infant approach,mother withdraw" touch pattern. Nonlinear analyses indicated that altered self- and interactive contingency were similar at both the low ("denial") as well as the high ("endorsement") poles of depressive symptoms, in half the findings. These complex, multimodal findings define different aspects of communication disturbance, with relevance for therapeutic intervention. [source]