ΔS=1\Delta S = 1 Hadronic Weak Decays of Hyperons in a Soliton Model

We study the parity violating hyperon non-leptonic weak decays in the three flavor Skyrme model. We follow the approach in which the symmetry breaking terms in the action are diagonalized exactly within the collective coordinate approximation. We show that although this method introduces some configuration mixing, the $\Delta I =1/2$ rule is numerically well satisfied. In addition, and in contrast to previous calculations, we show that not only the relative amplitudes are in good agreement with the empirical values but also their absolute values. The issue of whether the strong interaction enhancement factors should be included in soliton calculations is also addressed.Comment: 8 pages, LaTeX, no figure

Exact C=1 Boundary Conformal Field Theories

We present a solution of the problem of a free massless scalar field on the half line interacting through a periodic potential on the boundary. For a critical value of the period, this system is a conformal field theory with a non-trivial and explicitly calculable S-matrix for scattering from the boundary. Unlike all other exactly solvable conformal field theories, it is non-rational ({\it i.e.} has infinitely many primary fields). It describes the critical behavior of a number of condensed matter systems, including dissipative quantum mechanics and of barriers in ``quantum wires''.Comment: harvmac, 10 pages, PUPT-1432/IASSNS-HEP-93/7

On Topological Susceptibility, Vacuum Energy and Theta Dependence in Gluodynamics

We suggest that the topological susceptibility in gluodynamics can be found in terms of the gluon condensate using renormalizability and heavy fermion representation of the anomaly. Analogous relations can be also obtained for other zero momentum correlation functions involving the topological density operator. Using these relations, we find the theta dependence of the condensates , and of the partition function for small theta and an arbitrary number of colors.Comment: Details of the derivation are clarified, changes in discussions, new references are adde

Training Evaluation in Virtual Worlds: Development of a Model

Many organizations have adopted virtual worlds (VWs) as a setting for training programs; however, research on appropriate evaluation of training in this new setting is incomplete. In this article, we address this gap by first exploring the unique issues relevant to evaluation faced by training designers working in VWs. At the macro-organizational level, the primary issue faced is an organizational culture unreceptive to or otherwise skeptical of VWs. At the micro-organizational level, two major issues are identified: individual trainees unreceptive to VWs and general lack of experience navigating VWs. All three of these challenges and their interrelationships may lead to poor reactions, learning, and transfer from VW-based training despite strong, pedagogically sound training design. Second, we survey the training evaluation research literature, identifying the most well-supported training evaluation models, discussing the suitability of each for evaluating VW-based training. Third, we propose a new integrative model based upon this literature, incorporating solutions to the unique issues faced in VWs with the most relevant portions of the models discussed earlier. Fourth, broad thematic implications of this model are identified and applied to prior VW literature. Finally, we provide specific recommendations to practitioners and researchers to evaluate their VW-based training fully

The anomaly-free quantization of two-dimensional relativistic string. I

An anomaly-free quantum theory of a relativistic string is constructed in two-dimensional space-time. The states of the string are found to be similar to the states of a massless chiral quantum particle. This result is obtained by generalizing the concept of an ``operator'' in quantum field theory.Comment: LaTeX, 19 pages, no figure

D-Brane Interactions in a Gravitational Shock Wave Background

We study D-branes in the background of a gravitational shock wave. We consider the case of parallel D-branes located on opposite sides with respect to the shock wave. Their interaction is studied by evaluating the cylinder diagram using the boundary states technique. Boundary states are defined at each D-brane and their scalar product is evaluated after propagation through the shock wave. Taking the limit where the gravitational shock wave vanishes we show that the amplitude evaluated is consistent with the flat space-time result.Comment: To be published in Modern Physics Letters A, revised version with references added, 12 page

A new method of quantization of classical solutions

Using stochastic quantization method we derive equations for correlators of quantum fluctuations around the classical solution in the massless phi^4 theory. The obtained equations are then solved in the lowest orders of perturbation theory, and the first correction to the free propagator of a quantum fluctuation is calculated.Comment: 8 page

Boundary susceptibility in the spin-1/2 chain: Curie like behavior without magnetic impurities

We investigate the low-temperature thermodynamics of the spin-1/2 Heisenberg chain with open ends. On the basis of boundary conformal field theory arguments and numerical density matrix renormalization group calculations, it is established that in the isotropic case the impurity susceptibility exhibits a Curie-like divergent behavior as the temperature decreases, even in the absence of magnetic impurities. A similar singular temperature dependence is also found in the boundary contributions of the specific heat coefficient. In the anisotropic case, for $1/2<\Delta<1$, these boundary quantities still show singular temperature dependence obeying a power law with an anomalous dimension. Experimental consequences will be discussed.Comment: 5 pages, 1 figure, final versio

Towards the total synthesis of apo-neocarzinostatin

Neocarzinostatin is a dienediyne chromo protein antibiotic that is made up of a chromophore and an apoprotein (apo-Neocarzinostatin) in a 1:1 ratio. Neocarzinostatin (NCS) is an antitumor agent isolated from Streptomyces carzinostaticus that has shown the effective treatment against acute leukaemia and certain cancers. The aim of the project was to synthesize apo-Neocarzinostatin and there are currently no reports of it being synthesized. The C-terminal fragment was synthesized and did not require further purification. A 12-mer was synthesized that was not part of Apo-NCS but it showed that thioester fragments can be synthesized and cleaved successfully from the resin. Part of the middle fragment of Apo-NCS w as synthesized but only as far as 30 residues: also only SPPS was shown to be successful

On the next-to-leading-order correction to the effective action in N=2 gauge theories

I attempt to analyse the next-to-leading-order non-holomorphic contribution to the Wilsonian low-energy effective action in the four-dimensional N=2 gauge theories with matter, from the manifestly N=2 supersymmeric point of view, by using the harmonic superspace. The perturbative one-loop correction is found to be in agreement with the N=1 superfield calculations of de Wit, Grisaru and Rocek. The previously unknown coefficient in front of this non-holomorphic correction is calculated. A special attention is devoted to the N=2 superconformal gauge theories, whose one-loop non-holomorphic contribution is likely to be exact, even non-perturbatively. This leading (one-loop) non-holomorphic contribution to the LEEA of the N=2 superconformally invariant gauge field theories is calculated, and it does not vanish, similarly to the case of the N=4 super-Yang-Mills theory.Comment: 15 pages, LaTeX; changes in the abstract and in sect.