Dynamic mechanical analysis of fiber reinforced composites

Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus

Development and application of computer software techniques to human factors task data handling problems Final report, 21 Jun. 1965 - 21 Jun. 1966

Computer software techniques applied to human factors task data handling problem

An empirical study on the preferred size of the participant information sheet in research

Background: Informed consent is a requirement for all research. It is not, however, clear how much information is sufficient to make an informed decision about participation in research. Information on an online questionnaire about childhood development was provided through an unfolding electronic participant sheet in three levels of information. \ud Methods: 552 participants, who completed the web-based survey, accessed and spent time reading the participant information sheet (PIS) between July 2008 and November 2009. The information behaviour of the participants was investigated. The first level contained less information than might be found on a standard PIS, the second level corresponded to a standard PIS, and the third contained more information than on a standard PIS. The actual time spent on reading the information provided in three incremental levels and the participants' evaluation of the information were calculated. \ud Results: 77% of the participants chose to access the first level of information, whereas 12% accessed the first two levels, 6% accessed all three levels of information and 23% participated without accessing information. The most accessed levels of information were those that corresponded to the average reading times. \ud Conclusion: The brief information provided in the first level was sufficient for participants to make informed decisions, while a sizeable minority of the participants chose not to access any information at all. This study adds to the debate about how much information is required to make a decision about participation in research and the results may help inform the future development of information sheets by providing data on participants' actual needs when deciding about questionnaire surveys.\u

Do Shareholders' Preferences Affect their Funds' Management? Evidence from the Cross Section of Shareholders and Funds

We consider how fund managers respond to the conflicting preferences of their investors. We focus on the conflict between the taxable and retirement accounts of international funds, which face different tradeoffs between dividends and capital gains. In principle, managers could resolve this conflict through dividend arbitrage, but a proprietary database of dividend-arbitrage transactions shows that in practice they cannot. Thus, managers must resolve it through their investment policies, and we find robust evidence that managers with more retirement money favor the preferences of retirement investors. We find additional evidence in the difference between U.S. and Canadian funds' portfolio weights. Nous étudions comment les gestionnaires de fonds réagissent aux préférences contradictoires de leurs investisseurs. Notre étude se concentre principalement sur les conflits entre les comptes taxés et les comptes de retraite des fonds internationaux qui font l'objet de compromis différents entre les gains en dividendes et les gains de capital. En théorie, les gestionnaires peuvent résoudre ces conflits par des opérations d'arbitrage sur les dividendes, mais une base de données privée d'opérations d'arbitrage fait apparaître qu'en pratique ils ne peuvent pas. Les gestionnaires doivent alors résoudre ces conflits à travers leurs politiques d'investissement, et nous trouvons des résultats significatifs montrant que ceux dont le capital est issu majoritairement des retraites favorisent les investisseurs de fonds de pension. Nous trouvons également des différences entre les poids des portefeuilles de fonds américains et canadiens.Dividend arbitrage, tax efficiency, agency issues, mutual funds, arbitrage sur les dividendes, taxes sur les rendements, placements pour compte, fonds commun de placement

How and Why do Investors Trade Votes, and What Does it Mean?

The standard analysis of corporate governance is that shareholders vote in the ratios that firms choose, such as one-share-one-vote. But if the cost of unbundling and trading votes is sufficiently low, then shareholders vote in the ratios that they themselves choose. We document an active market for votes within the equity-loan market, where we find that the average vote sells for zero. We hypothesize that asymmetric information motivates these vote reallocations, and we find support for this view in the cross section of votes: there is more trade for higher-spread firms and more for poor performers, especially when the vote is close. We also find that the vote reallocations correspond to support for shareholder proposals and opposition to management proposals. L'analyse classique de la gouvernance d'entreprise suppose que les actionnaires votent selon les modalités choisies par la firme, par exemple un vote par action. Mais si les coûts associés à la séparation et à l'échange des votes sont suffisamment faibles, alors les actionnaires votent selon les modalités qu'ils ont eux-mêmes choisies. Nous présentons le cas d'un marché actif de votes au sein du marché des mises de fonds sous forme d'emprunts (equity loans), où nous constatons qu'en moyenne les votes se vendent pour rien. Nous supposons que l'asymétrie d'information provoque cette réallocation des votes, et nous étayons cette hypothèse à travers l'étude transversale des votes : le nombre d'opérations est plus important pour les compagnies dont l'écart acheteur-vendeur est plus élevé ainsi que pour celles dont les résultats sont plus faibles, particulièrement lorsque le vote est clos. Cette étude montre aussi que la réallocation des votes permet de soutenir les propositions des actionnaires et de s'opposer à celles des gestionnaires.vote trading, corporate governance, equity lending, information asymmetry, transaction de votes, gouvernance d'entreprise, prêt d'actions, asymétrie d'information

Absence of reflection as a function of the coupling constant

We consider solutions of the one-dimensional equation $-u'' +(Q+ \lambda V) u = 0$ where $Q: \mathbb{R} \to \mathbb{R}$ is locally integrable, $V : \mathbb{R} \to \mathbb{R}$ is integrable with supp$(V) \subset [0,1]$, and $\lambda \in \mathbb{R}$ is a coupling constant. Given a family of solutions $\{u_{\lambda} \}_{\lambda \in \mathbb{R}}$ which satisfy $u_{\lambda}(x) = u_0(x)$ for all $x<0$, we prove that the zeros of $b(\lambda) := W[u_0, u_{\lambda}]$, the Wronskian of $u_0$ and $u_{\lambda}$, form a discrete set unless $V \equiv 0$. Setting $Q(x) := -E$, one sees that a particular consequence of this result may be stated as: if the fixed energy scattering experiment $-u'' + \lambda V u = Eu$ gives rise to a reflection coefficient which vanishes on a set of couplings with an accumulation point, then $V \equiv 0$.Comment: To appear in Journal of Mathematical Physic

A VLSI design for a systolic Viterbi decoder

A systolic Viterbi decoder for convolutional codes is developed. This decoder uses the trace-back method to reduce the amount of data needed to be stored in registers. It is shown that this new algorithm requires a smaller chip size and achieves a faster decoding time than other existing methods

Visualising uncertainty: examining women's views on the role of Magnetic Resonance Imaging (MRI) in late pregnancy

Prenatal screening occupies a prominent role within sociological debates on medical uncertainty. A particular issue concerns the limitations of routine screening which tends to be based on risk prediction. Computer assisted visual technologies such as Magnetic Resonance Imaging (MRI) are now starting to be applied to the prenatal realm to assist in the diagnosis of a range of fetal and maternal disorders (from problems with the fetal brain to the placenta). MRI is often perceived in popular and medical discourse as a technology of certainty and truth. However, little is known about the use of MRI as a tool to confirm or refute the diagnosis of a range of disorders in pregnancy. Drawing on qualitative research with pregnant women attending a fetal medicine clinic in the North of England this paper examines the potential role that MRI can play in mediating pregnancy uncertainty. The paper will argue that MRI can create and manage women's feelings of uncertainty during pregnancy. However, while MRI may not always provide women with unequivocal answers, the detailed information provided by MR images combined with the interpretation and communication skills of the radiologist in many ways enables women to navigate the issue. Our analysis of empirical data therefore highlights the value of this novel technological application for women and their partners. It also seeks to stress the merit of taking a productive approach to the study of diagnostic uncertainty, an approach which recognises the concepts dual nature

Bound States at Threshold resulting from Coulomb Repulsion

The eigenvalue absorption for a many-particle Hamiltonian depending on a parameter is analyzed in the framework of non-relativistic quantum mechanics. The long-range part of pair potentials is assumed to be pure Coulomb and no restriction on the particle statistics is imposed. It is proved that if the lowest dissociation threshold corresponds to the decay into two likewise non-zero charged clusters then the bound state, which approaches the threshold, does not spread and eventually becomes the bound state at threshold. The obtained results have applications in atomic and nuclear physics. In particular, we prove that atomic ion with atomic critical charge $Z_{cr}$ and $N_e$ electrons has a bound state at threshold given that $Z_{cr} \in (N_e -2, N_e -1)$, whereby the electrons are treated as fermions and the mass of the nucleus is finite.Comment: This is a combined and updated version of the manuscripts arXiv:math-ph/0611075v2 and arXiv:math-ph/0610058v