Cognitive mechanisms underlying instructed choice exploration of small city maps

We investigated the cognitive mechanisms underlying the exploration and decision-making in realistic and novel environments. Twelve human subjects were shown small circular U.S. city maps with two locations highlighted on the circumference, as possible choices for a post office (“targets”). At the beginning of a trial, subjects fixated a spot at the center of the map and ultimately chose one of the two locations. A space syntax analysis of the map paths (from the center to each target) revealed that the chosen location was associated with the less convoluted path, as if subjects navigated mentally the paths in an “ant's way,” i.e., by staying within street boundaries, and ultimately choosing the target that could be reached from the center in the shortest way, and the fewest turns and intersections. The subjects' strategy for map exploration and decision making was investigated by monitoring eye position during the task. This revealed a restricted exploration of the map delimited by the location of the two alternative options and the center of the map. Specifically, subjects explored the areas around the two target options by repeatedly looking at them before deciding which one to choose, presumably implementing an evaluation and decision-making process. The ultimate selection of a specific target was significantly associated with the time spent exploring the area around that target. Finally, an analysis of the sequence of eye fixations revealed that subjects tended to look systematically toward the target ultimately chosen even from the beginning of the trial. This finding indicates an early cognitive selection bias for the ensuing decision process

T-Violation in K+→μ+νγK^+ \to \mu^+ \nu \gamma Decay And Supersymmetry

Measurement of the transverse muon polarization $P^{\bot}_{\mu}$ in the $K^+ \rightarrow \mu^+\nu\gamma$ decay will be attempted for the first time at the ongoing KEK E246 experiment and also at a proposed BNL experiment. We provide a general analysis of how $P^{\bot}_{\mu}$ is sensitive to the physical $CP$-violating phases in new physics induced four-Fermi interactions, and then we calculate the dominant contributions to $P^{\bot}_{\mu}$ from squark family mixings in generic supersymmetric models. Estimates of the upper bounds on $P^{\bot}_{\mu}$ are also given. It is found that a supersymmetry-induced right-handed quark current from $W$ boson exchange gives an upper limit on $P^{\bot}_{\mu}$ as large as a few per cent, whereas with charged-Higgs-exchange induced pseudoscalar interaction, $P^{\bot}_{\mu}$ is no larger than a few tenths of a per cent. Possible correlations between the muon polarization measurements in $K^+ \rightarrow \mu^+\nu\gamma$ and $K^+ \rightarrow \pi^0\mu^+\nu$ decays are discussed, and distinctive patterns of this correlation from squark family-mixings and from the three-Higgs-doublet model are noted.Comment: Revtex, 29 pages including 4 epsf figure

Supersymmetric Time Reversal Violation in Semileptonic Decays of Charged Mesons

We provide a general analysis of time reversal violation arising from misalignment between quark and squark mass eigenstates. In particular, we focus on the possibility of large enhancement effects due to the top quark mass. For semileptonic decays of the charged mesons, $K^+ \rightarrow \pi^0 \mu^+ \nu_{\mu}$, $D^+ \rightarrow \overline{K}^0 \mu^+ \nu_{\mu}$, and $B^+ \rightarrow \overline{D}^0 \tau^+ \nu_{\tau}$, the transverse polarization of the lepton $P^{\bot}_l$ is a $T$-odd observable that is of great experimental interest. It is noted that under favorable choice of parameters, $P^{\bot}_{\mu}$ in $K^+_{\mu3}$ decay can be detectable at the ongoing KEK experiment and it holds a promising prospect for discovery at the proposed BNL experiment. Furthermore, $P^{\bot}_{\tau}$ in $B^{\pm}$ decay could well be within the reach of $B$ factories, but $P^{\bot}_{\mu}$ in $D^{\pm}$ decay is not large enough for detection at the proposed $\tau$-charm factory.Comment: LaTex, 14 pages, 2 figures, minor changes, version to appear in Phys. Lett.

CP violation in chargino decays in the MSSM

In the minimal supersymmetric standard model (MSSM) with complex parameters, supersymmetric loop effects can lead to \emph{CP} violation. We calculate the rate asymmetries of decays of charginos into the lightest neutralino and a $W$ boson on the basis of the most important loop contributions in the third generation squark sectors. It turns out that the \emph{CP} violating asymmetries can be a few per cent in typical regions of the parameter space of the MSSM. These processes would provide very promising channels for probing \emph{CP} violation in the MSSM at future high-energy colliders.Comment: 15 pages, 5 figures, LaTeX2

Standard SANC modules for NLO QCD Radiative Corrections to Single-top Production

It this paper we present the results obtained with the newly created Standard SANC modules for calculation of the NLO QCD corrections to single top production processes in s and t channels at the partonic level, as well as top-decays. The main aim of these results is to prove the correct work of modules. A comprehensive comparison with results of the CompHEP system is given, where possible. These modules are intended to be used in Monte Carlo generators for single top production processes at the LHC. As in our recent paper, devoted to the electroweak corrections to these processes, we study the regularization of the top-legs associated infrared divergences with aid of the complex mass of the top quark. A comparison of QCD corrections with those computed by the conventional method is presented both for top production and decays. For s channel production we give an analytic proof of equivalence of the two methods in the limit of low top width.Comment: 21 pages, 2 figures, 17 table

Two-Fermion Production in Electron-Positron Collisions

This report summarizes the results of the two-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the theoretical calculations of the two fermion production process in the electron-positron collision at LEP2 center of the mass energies are reported. The Bhabha process and the production of muon, tau, neutrino and quark pairs is covered. On the basis of comparison of various calculations, theoretical uncertainties are estimated and compared with those needed for the final LEP2 data analysis. The subjects for the further studies are identified.Comment: 2-fermion working group report of the LEP2 Monte Carlo Workshop 1999/2000, 113 pages, 24 figures, 35 table

Conformational effects on the Circular Dichroism of Human Carbonic Anhydrase II: a multilevel computational study

Circular Dichroism (CD) spectroscopy is a powerful method for investigating conformational changes in proteins and therefore has numerous applications in structural and molecular biology. Here a computational investigation of the CD spectrum of the Human Carbonic Anhydrase II (HCAII), with main focus on the near-UV CD spectra of the wild-type enzyme and it seven tryptophan mutant forms, is presented and compared to experimental studies. Multilevel computational methods (Molecular Dynamics, Semiempirical Quantum Mechanics, Time-Dependent Density Functional Theory) were applied in order to gain insight into the mechanisms of interaction between the aromatic chromophores within the protein environment and understand how the conformational flexibility of the protein influences these mechanisms. The analysis suggests that combining CD semi empirical calculations, crystal structures and molecular dynamics (MD) could help in achieving a better agreement between the computed and experimental protein spectra and provide some unique insight into the dynamic nature of the mechanisms of chromophore interactions

Responsive glyco-poly(2-oxazoline)s: synthesis, cloud point tuning, and lectin binding

A new sugar-substituted 2-oxazoline monomer was prepared using the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. Its copolymerization with 2-ethyl-2-oxazoline as well as 2-(dec-9-enyl)-2-oxazoline, yielding well-defined copolymers with the possibility to tune the properties by thiol-ene "click" reactions, is described. Extensive solubility studies on the corresponding glycocopolymers demonstrated that the lower critical solution temperature behavior and pH-responsiveness of these copolymers can be adjusted in water and phosphate-buffered saline (PBS) depending on the choice of the thiol. By conjugation of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose and subsequent deprotection of the sugar moieties, the hydrophilicity of the copolymer could be increased significantly, allowing a cloud-point tuning in the physiological range. Furthermore, the binding capability of the glycosylated copoly(2-oxazoline) to concanavalin A was investigated

Testing Time Reversal Invariance in Exclusive Semileptonic B Meson Decays

We demonstrate that polarization measurements in exclusive semileptonic B decays are powerful tools for unraveling non-standard model sources of T-violation. Measurements of the transverse polarization of the tau lepton in the B to D tau nu and B to D* tau nu decays probe separately effective scalar and pseudoscalar CP-violating four-Fermi interactions, whereas the D* polarization in the B to D* l nu (l=e,mu) decay is sensitive to an effective right-handed quark current interaction. Two T-odd polarization structures exist involving the D* polarization and they can be isolated and studied separately. An estimate of these T-odd effects is also given in the context of supersymmetric theories.Comment: RevTex, 13 pages, minor changes, version to appear in PL

Neutral Higgs bosons in the MNMSSM with explicit CP violation

Within the framework of the minimal non-minimal supersymmetric standard model (MNMSSM) with tadpole terms, CP violation effects in the Higgs sector are investigated at the one-loop level, where the radiative corrections from the loops of the quark and squarks of the third generation are taken into account. Assuming that the squark masses are not degenerate, the radiative corrections due to the stop and sbottom quarks give rise to CP phases, which trigger the CP violation explicitly in the Higgs sector of the MNMSSM. The masses, the branching ratios for dominant decay channels, and the total decay widths of the five neutral Higgs bosons in the MNMSSM are calculated in the presence of the explicit CP violation. The dependence of these quantities on the CP phases is quite recognizable, for given parameter values.Comment: 25 pages, 8 figure