Abstract:
Background: Since 2004, zebrafish have become the
state-of-the-art, in vivo model for biomedical
research due to their genetic and physiological homology with humans,
inexpensive high-quantity breeding, and quick development in a
highly-controlled environment suitable for longitudinal studies. New Method: To fully utilize the zebrafish model, a novel, automated, high-throughput system
was designed. Shoals of five zebrafish were placed in 16 tanks and automatically
fed over two days for a total of 16 training sessions. Color LED lights were
used as the stimulus for each shoal coinciding with the release of food for a
duration of 20 seconds. This system was tested on two age groups: 6- and 11-month-old. Results: After three training sessions, the median height of the school in the
tank during stimulus was significantly higher than that of the naïve fish
during the first training session. All subsequent training sessions demonstrated
similar behaviour. A decline in memory retention, as defined by a reduction in
the median height during light stimulus (i.e. no simultaneous food delivery),
was observed 8 days post training. Comparison with existing methods:The
high-throughput nature of this system allows for simultaneous training of 16
tanks of fish under identical conditions without human interaction and provides
a means to rapidly assess their learning and memory behaviours. Conclusion: Results provide a baseline for understanding the normal cognitive processes
of learning and memory retention in zebrafish. This work paves the way for
future studies on the impacts of therapeutic agents on these cognitive processes.

Abstract:
We give a preliminary report on the hadron spectrum on an ensemble of quenched lattices at $\beta$ values of 6.0, 6.2 and 6.4, using staggered fermions and collaborators Rajan Gupta and Steve Sharpe. Because of the relatively small number of configurations we pay marginally more attention to the question of statistics than in previous analyses. We are unable to discredit quenched QCD.

Abstract:
We report progress in our lattice study of hadronic weak matrix elements relevant for the Delta I = 1/2 rule and epsilon-prime. The presented results are from our first runs on a quenched ensemble with beta=6.0 and a dynamical Nf=2 ensemble with beta=5.7, using staggered gauge-invariant tadpole-improved operators.

Abstract:
We use lattice topology as a laboratory to compare the Wilson action (WA) with the Symanzik-Weisz (SW) action constructed from a combination of (1x1) and (1x2) Wilson loops, and the estimate of the renormalization trajectory (RT) from a renormalization group transformation (RGT) which also includes higher representations of the (1x1) loop. Topological charges are computed using the geometric (L\"uscher's) and plaquette methods on the uncooled lattice, and also by using cooling to remove ultraviolet artifacts. We show that as the action improves by approaching the RT, the topological charges for individual configurations computed using these three methods become more highly correlated, suggesting that artificial lattice renormalizations to the topological susceptibility can be suppressed by improving the action.

Abstract:
We have constructed the lowest few eigenvectors of the staggered Dirac operator on SU(3) gauge configurations, both quenched and dynamical. We use these modes to study the topological charge and to construct approximate hadronic correlators.

Abstract:
We have computed the eta-prime pseudoscalar octet mass splitting using staggered fermions on both dynamical and quenched gauge configurations. We have used Wuppertal smeared operators to reduce excited state contributions. We compare our results with the theoretical forms predicted by partially quenched chiral perturbation theory in the lowest order. Using lattice volumes of size 16^3 x 32 with a^{-1}=2GeV we obtain results consistent with the physical eta-prime mass. We also demonstrate that the flavor singlet piece of the eta-prime mass comes from zero modes of the Dirac operator.

Abstract:
We perform a study of matrix elements relevant for the Delta I=1/2 rule and the direct CP-violation parameter epsilon-prime from first principles by computer simulation in Lattice QCD. We use staggered (Kogut-Susskind) fermions, and employ the chiral perturbation theory method for studying K to 2 Pi decays. Having obtained a reasonable statistical accuracy, we observe an enhancement of the Delta I=1/2 amplitude, consistent with experiment within our large systematic errors. Finite volume and quenching effects have been studied and were found small compared to noise. The estimates of epsilon-prime are hindered by large uncertainties associated with operator matching. In this paper we explain the simulation method, present the results and address the systematic uncertainties.

Abstract:
We present our latest results for the Delta I=1/2 rule, obtained on quenched ensembles with beta=6.0 and 6.2, and a set of N_f=2 configurations with beta=5.7. The statistical noise is quite under control. We observe an enhancement of the Delta I=1/2 amplitude consistent with experiment, although the systematic errors are still large. We also present a non-perturbative determination of Z_P, Z_S and the strange quark mass. We briefly discuss our progress in calculating epsilon-prime.

Abstract:
We have gained enough statistical precision to distinguish signal from noise in matrix elements of all operators relevant for the Delta I=1/2 rule in kaon decays and for the direct CP violation parameter epsilon-prime. We confirm significant enhancement of Delta I=1/2 transitions observed in experiments, although a few large systematic uncertainties remain in our predictions: higher-order chiral corrections and lattice spacing dependence. The estimate of epsilon-prime parameter is further complicated by the problem of matching lattice and continuum operators.

Abstract:
We calculate the kaon $B$-parameter in quenched lattice QCD at $\beta=6.0$ using Wilson fermions at $\kappa=0.154$ and $0.155$. We use two kinds of non-local (``smeared'') sources for quark propagators to calculate the matrix elements between states of definite momentum. The use of smeared sources yields results with much smaller errors than obtained in previous calculations with Wilson fermions. By combining results for $\vec p =(0,0,0)$ and $\vec p =(0,0,1)$, we show that one can carry out the non-perturbative subtraction necessary to remove the dominant lattice artifacts induced by the chiral symmetry breaking term in the Wilson action. Our final results are in good agreement with those obtained using staggered fermions. We also present results for $B$-parameters of the $\Delta I = 3/2$ part of the electromagnetic penguin operators, and preliminary results for \bk\ in the presence of two flavors of dynamical quarks.