Falling chains

The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is incorrect because it neglects the energy gained when a transferred link leaves a subchain. The maximum chain tension measured by Calkin and March for the falling folded chain is given a simple if rough interpretation. Other aspects of this falling folded chain are briefly discussed.Comment: 9 pages, 1 figure; the Abstract has been shortened, three paragraphs have been re-written for greater clarity, and textual improvements have been made throughout the paper; to be published by the Am. J. Physic

Price and volatility behaviour of four Asian stock markets

The past ten years have witnessed many changes in the Asian economies and stock markets, particularly in the Four Tigers, Hong Kong, Singapore, South Korea and Taiwan. They enjoyed economic growth well above the world average during the late 1980s and early 1990s. There were sharp increases in their stock market capitalisations against the background of low growth and low interest rates in the US and European countries in the early 1990s. This coincided with the time when measures to liberalise these markets were implemented to allow or attract foreign direct investments in their stock markets. Then by mid 1997, both their economies and stock markets began to slump. This ten year time period thus provides a good opportunity to examine how such economic and institutional changes affected the price and volatility behaviour of the Four Tigers and their relationships with other markets. Overall, the findings of the thesis suggest that with the increase in foreign participation in the four individual markets, the influence of noise trading activities has been reduced through more and better informed trading. However, their relationships with three world major markets, the US, the UK and Japan, are not getting much stronger. There is no evidence to suggest that their prices are being increasingly led by the world markets, nor is their volatility becoming more sensitive to foreign news. Their price and volatility relationships with three regional markets, Thailand, Malaysia and Indonesia, were not particularly strong either, until recently, when the Asian financial crisis has made them more responsive to shocks from one another. The message to the governments of the Four Tigers is clear. Foreign direct equity investments have not destabilised their stock markets. Instead, the mismanagement of their own and/or their trading partners' economies should be held more responsible

Relative contributions of consonants and vowels to Mandarin sentence intelligibility

This study investigated the relative contributions of consonants and vowels to Mandarin sentence intelligibility using a noise replacement paradigm. In Experiment 1, 20 young normal-hearing native Mandarin listeners recognized Mandarin sentences with various amounts of segmental information preserved. Results showed that the vowel-only sentences (consonants replaced by noise) yielded a remarkable 3:1 intelligibility advantage over the consonant-only sentences (vowels replaced by noise). This ratio was larger than that found in English, suggesting that vowels contribute more to sentence intelligibility in Mandarin than in English. Intelligibility increased significantly when a little portion at vowel onsets was added to the consonant-only sentences. However, intelligibility of the vowel-only sentences was still maintained high when the same portion of vowel onsets and an equal amount of vowel offsets were replaced by noise, suggesting that vowel onsets contain redundant information to vowel centers for Mandarin sentence recognition. In Experiment 2, the same listeners discriminated tones of vowels with various durations preserved at either onsets or centers. Results were compared with the findings in Experiment 1, and suggested that lexical tones are relatively redundant for Mandarin sentence intelligibility in quiet.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

Design characteristics of a piezoelectric/ER fluid motor

This paper shows the performance characteristics of a new concept in stepper motor technology. Piezo translators [PZT] employed to provide primary motion are connected to a load via a controllable electrorheological fluid [ERF] ratchet. The speed of the motor is governed by either the frequency of the pulse control or the amplitude of expansion of the PZT. Ideal considerations are used to quantify the limiting potential of the drive. Future applications are discussed.published_or_final_versio

Singularity-Free Breit Equation from Constraint Two-Body Dirac Equations

We examine the relation between two approaches to the quantum relativistic two-body problem: (1) the Breit equation, and (2) the two-body Dirac equations derived from constraint dynamics. The Breit equation is known to be pathological when singularities appear at finite separations $r$ in the reduced set of coupled equations for attractive potentials even when the potentials themselves are not singular there. They then give rise to unphysical bound states and resonances. In contrast, the two-body Dirac equations of constraint dynamics do not have these pathologies in many nonperturbative treatments. To understand these marked differences, we first express these contraint equations in a hyperbolic form. These coupled equations are then re-cast into two equivalent equations: (1) a covariant Breit-like equation with potentials that are exponential functions of certain ``generator'' functions, and (2) a covariant orthogonality constraint on the relative momentum. This reduction enables us to show in a transparent way that finite-$r$ singularities do not appear as long as the the exponential structure is not tampered with and the exponential generators of the interaction are themselves nonsingular for finite $r$. These Dirac or Breit equations, free of the structural singularities which plague the usual Breit equation, can then be used safely under all circumstances, encompassing numerous applications in the fields of particle, nuclear, and atomic physics which involve highly relativistic and strong binding configurations.Comment: 38 pages (REVTeX), (in press in International Journal of Modern Physics

Verbal abuse in married versus non-married couples: the relationship between perception of acceptability and experience

Verbal abuse can lead to physical abuse if it is not recognized, or is tolerated in one\u27s partner. Participant\u27s perception of the acceptability of verbal abuse (PAVA) was compared to the level of verbal abuse in their own relationship (Conflict Tactics Scales-II). PAVA had a weak positive relationship with the actual occurrence of verbal abuse. PAVA and levels of verbal abuse were highest in very new and more established relationships regardless of relationship status. Males were more accepting of verbal abuse, and reported it less in their relationships. Finally, African American, Hispanic American and Asian American participants reported lower levels of verbal abuse in their relationships. These findings illustrate the complex relationship between the perception and experience of verbal abuse and suggest the need for additional research

Electroproduction of the d* dibaryon

The unpolarized cross section for the electroproduction of the isoscalar $J^\pi = 3^+$ di-delta dibaryon $d^*$ is calculated for deuteron target using a simple picture of elastic electron-baryon scattering from the $\Delta \Delta (^7D_1)$ and the $NN (^3S_1)$ components of the deuteron. The calculated differential cross section at the electron lab energy of 1 GeV has the value of about 0.24 (0.05) nb/sr at the lab angle of 10$^\circ$ (30$^\circ$) for the Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross section decreases rapidly with increasing dibaryon mass. A large calculated width of 40 MeV for $d^*(\Delta\Delta ^7S_3)$ combined with a small experimental upper bound of 0.08 MeV for the $d^*$ decay width appears to have excluded any low-mass $d^*$ model containing a significant admixture of the $\Delta\Delta (^7S_3)$ configuration.Comment: 11 journal-style pages, 8 figure