On the Acquisition of Universal and Parameterised Goal Accessibility Constraints by Japanese Learners of English

This paper reports on how adult Japanese Learners of English/JLEs acquire universal and parameterised constraints which regulate the accessibility of Goals to Wh-Movement, and which determine whether subordinate or superordinate material is pied-piped or stranded when a wh-word is moved. We present evidence that universal constraints on Goal Accessibility operate in early JLE grammars, and that learners initially transfer setting for parameterised constraints from L1 to L2, concluding that our overall findings are broadly consistent with the Full Transfer Full Access model of L2 acquisition developed in Schwarz and Sprouse (1994, 1996). We show that JLEs are able to reset some parameterised constraints (e.g. the P-Stranding Constraint) but not others (e.g. the Left Branch Condition), and argue that they are only able to re-set learnable parameterised constraints (i.e. those whose setting can be learned solely on the basis of positive evidence from input), not unlearnable parameterised constraints (i.e. those whose settings cannot be learned solely on the basis of positive input)

Solutions of polynomial Pell's equation

AbstractLet D=F2+2G be a monic quartic polynomial in Z[x], where degG<degF. Then for F/G∈Q[x], a necessary and sufficient condition for the solution of the polynomial Pell's equation X2−DY2=1 in Z[x] has been shown. Also, the polynomial Pell's equation X2−DY2=1 has nontrivial solutions X,Y∈Q[x] if and only if the values of period of the continued fraction of D are 2, 4, 6, 8, 10, 14, 18, and 22 has been shown. In this paper, for the period of the continued fraction of D is 4, we show that the polynomial Pell's equation has no nontrivial solutions X,Y∈Z[x]

Vanishing Thermal Mass in the Strongly Coupled QCD/QED medium

In this paper we perform a nonperturbative analysis of a thermal quasifermion in thermal QCD/QED by studying its self-energy function through the Dyson-Schwinger equation with the hard-thermal-loop resummed improved ladder kernel. Our analysis reveals several interesting results, some of which may force us to change the image of the thermal quasifermion: (1) The thermal mass of a quasifermion begins to decrease as the coupling gets stronger and finally disappears in the strong coupling region,(2) the imaginary part of the chiral invariant mass function (i.e., the decay width of the quasifermion) persists to have $O(g^2 T \log (1/g))$ behavior. Present results suggest that in the recently produced strongly coupled quark-gluon-plasma, the thermal mass of a quasifermion should vanish. We also briefly comment on evidence of the existence of a massless, or an ultrasoft mode.Comment: 6 pages, 8 figures, Published versio

Locking Local Oscillator Phase to the Atomic Phase via Weak Measurement

We propose a new method to reduce the frequency noise of a Local Oscillator (LO) to the level of white phase noise by maintaining (not destroying by projective measurement) the coherence of the ensemble pseudo-spin of atoms over many measurement cycles. This scheme uses weak measurement to monitor the phase in Ramsey method and repeat the cycle without initialization of phase and we call, "atomic phase lock (APL)" in this paper. APL will achieve white phase noise as long as the noise accumulated during dead time and the decoherence are smaller than the measurement noise. A numerical simulation confirms that with APL, Allan deviation is averaged down at a maximum rate that is proportional to the inverse of total measurement time, tau^-1. In contrast, the current atomic clocks that use projection measurement suppress the noise only down to the level of white frequency, in which case Allan deviation scales as tau^-1/2. Faraday rotation is one of the possible ways to realize weak measurement for APL. We evaluate the strength of Faraday rotation with 171Yb+ ions trapped in a linear rf-trap and discuss the performance of APL. The main source of the decoherence is a spontaneous emission induced by the probe beam for Faraday rotation measurement. One can repeat the Faraday rotation measurement until the decoherence become comparable to the SNR of measurement. We estimate this number of cycles to be ~100 cycles for a realistic experimental parameter.Comment: 18 pages, 7 figures, submitted to New Journal of Physic

Chiral Phase Transitions in QCD at Finite Temperature: Hard-Thermal-Loop Resummed Dyson-Schwinger Equation in the Real Time Formalism

Chiral phase transition in thermal QCD is studied by using the Dyson-Schwinger (DS) equation in the real time hard thermal loop approximation. Our results on the critical temperature and the critical coupling are significantly different from those in the preceding analyses in the ladder DS equation, showing the importance of properly taking into account the essential thermal effects, namely the Landau damping and the unstable nature of thermal quasiparticles.Comment: 4 pages including 2 figures (ps file), to appear in the proceedings of the 4th International Conference on Physics and Astrophysics of Quark-Gluon Plasma (ICPAQGP-2001), 26-30 November 2001, Jaipur, Indi