Search for the decay KL --> pi(0)e+e-

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level.     

Branching ratio measurement of the decay K(L) --> e(+)e(-)mu(+)mu(-)

We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution.     

Vagueness, ignorance, and margins for error

We argue that the epistemic theory of vagueness cannot adequately justify its key tenet-that vague predicates have precisely bounded extensions, of which we are necessarily ignorant. Nor can the theory adequately account for our ignorance of the truth values of borderline cases. Furthermore, we argue that Williamson’s promising attempt to explicate our understanding of vague language on the model of a certain sort of “inexact knowledge” is at best incomplete, since certain forms of vagueness do not fit Williamson’s model, and in fact fit an alternative model. Finally, we point out that a certain kind of irremediable inexactitude postulated by physics need not be-and is not commonly-interpreted as epistemic. Thus, there are aspects of contemporary science that do not accord well with the epistemicist outlook.     

Phase conjugation by degenerate four wave mixing in InSb with a cw CO laser

Degenerate four wave mixing (DFWM) in indium antimonide has been observed at 80 K with a low power c.w. CO laser. Phase conjugate reflectivities of up to 20% have been observed without saturation effects. In addition, a cross-modulation component has been identified which co-exists with the DFWM signal. From the experimental results a third order nonlinear susceptibility x⁽³⁾ = 1.1 ± 0.3 esu has been established.     

Identification of threo-ig-fluoro.9,10-Dihydroxystearic acid:a novel cofluorinated fatty acid from dichapetalum toxicarium seeds.

A novel co-fluorinated fatty acid has been isolated from seeds of Dichapetalum toxicarium and identified as threo-18-fluoro-9,10-dihydroxystearic acid (1).     

Measurement of the K(L) charge asymmetry

We present a measurement of the charge asymmetry delta(L) in the mode K(L)-->pi(+/-)e(-/+)nu based on 298 x 10(6) analyzed decays. We measure a value of delta(L) = [3322+/-58(stat)+/-47(syst)]x10(-6), in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and DeltaS = DeltaQ violation in the neutral kaon system.     

Single‐Molecule Determination of the Isomers of d‐Glucose and d‐Fructose that Bind to Boronic Acids

Monosaccharides, such as d ‐glucose and d ‐fructose, exist in aqueous solution as an equilibrium mixture of cyclic isomers and can be detected with boronic acids by the reversible formation of boronate esters. The engineering of accurate, discriminating and continuous monitoring devices relies on knowledge of which cyclic isomer of a sugar binds to a boronic acid receptor. Herein, by monitoring fluctuations in ionic current, we show that an engineered α‐hemolysin (αHL) nanopore modified with a boronic acid reacts reversibly with d ‐glucose as the pyranose isomer (α‐d ‐glucopyranose) and d ‐fructose as either the furanose (β‐d ‐fructofuranose) or the pyranose (β‐d ‐fructopyranose). Both of these binding modes contradict current binding models. With this knowledge, we distinguished the individual sugars in a mixture of d ‐maltose, d ‐glucose, and d ‐fructose.