Measurement of the K0 charge radius and a CP-violating asymmetry and a search for CP-violating E1 direct photon emission in the rare decay KL--> pi+ pi- e+ e-

Using the complete KTeV data set of 5,241 candidate K(L)--> pi(+) pi(-) e(+) e(-) decays (including an estimated background of 204 +/- 14 events), we have measured the coupling g(CR)= 0.163 +/- 0.0149(stat) +/- 0.023(syst) of the CP conserving charge radius process and from it determined a K(0) charge radius of = [-0.077 +/- 0.007(stat) +/- 0.011(syst)]fm(2). We have determined a first experimental upper limit of 0.04 (90% C.L.) /g(e1)/ / /g(M1)/ of the couplings for the E1 and M1 direct photon emission processes. We also report the measurement of /g(M1)/ including a vector form factor /g(M1)/(1 + (a(1)/a(2))/((M(2)(p)-(M(2)(k))= 2M(K)E(gamma*)), where vector /g(M1)/= 1.11+/- 0.12(stat) +/- 0.08(syst) and a(1)/a(2) = [-0.744 +/- 0.027(stat) +/- 0.032(syst)] GeV(2)/c(2). Finally, a CP-violating asymmetry of [13.6 +/- 1.4(stat) +/- 1.5(syst)]% in the CP and T odd angle phi between the decay planes of the e(+) e(-) and pi(+) pi(-) pairs in the K(L) center of mass is reported.     

Selected growth of cubic and hexagonal GaN epitaxial films on polar MgO(111)

Selected molecular beam epitaxy of zinc blende (111) or wurtzite (0001) GaN films on polar MgO(111) is achieved depending on whether N or Ga is deposited first. The cubic stacking is enabled by nitrogen-induced polar surface stabilization, which yields a metallic MgO(111)-(1 x 1)-ON surface. High-resolution transmission electron microscopy and density functional theory studies indicate that the atomically abrupt semiconducting GaN(111)/MgO(111) interface has a Mg-O-N-Ga stacking, where the N atom is bonded to O at a top site. This specific atomic arrangement at the interface allows the cubic stacking to more effectively screen the substrate and film electric dipole moment than the hexagonal stacking, thus stabilizing the zinc blende phase even though the wurtzite phase is the ground state in the bulk.     

Laser hazard evaluation method for middle infrared laser systems

Hazard evaluation methods for lasers, with wavelengths greater than 1.4 microns (mostly in the middle infrared), have changed significantly in the current version of the American National Standard for the Safe Use of Lasers, ANSI Z136.1-1993. A correct evaluation involves comparing the hazard potential based on two evaluation models; one based on individual pulses and the other based on an equivalent continuous-wave exposure. An example of the hazard evaluation method within this spectral region is provided.     

UNISOR on-line nuclear orientation facility (UNISOR/NOF)

The UNISOR on-line nuclear orientation facility (UNISOR/NOF) consists of a₃He−₄He dilution refrigerator on line to the isotope separator. Nuclei are implanted directly into a target foil which is soldered to the bottom accessed cold finger of the refrigerator. A 1.5 T superconducting magnet polarizes the ferromagnetic target foils and determines the axis of symmetry. Up to eight gamma detectors can be positioned around the refrigerator, each 9 cm from the target. A unique feature of this system is that the k=4 term in the directional distribution function can be directly and unambigously deduced so that a single solution for the mixing ratio can be found. The first on-line experiment at this facility reported here was a study of the decay of the¹⁹¹Hg and¹⁹³Hg isotopes.     

Microchemical investigation of medicinal plants. IV

Summary Chemical reactions and classification tests of the yellow crystalline solid isolated from the seeds of the catalpa tree have been carried out in the mg-scale. The compound contains only carbon, hydrogen and oxygen. but elemental analysis could not decide the molecular formula to be C₁₄H₁₂O₅ or C₁₇H₁₄O₆. Functional group determinations have established the presence of 2 hydroxyl and 2 methoxyl groups. A report on spectroscopic investigations will follow.

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Zusammenfassung Chemische Reaktionen und Vorproben für die gelbe kristallisierte Substanz aus dem Samen des Catalpa-Baumes wurden im Milligrammaßstab ausgeführt. Die Substanz enthält nur C, H und O, aber es gelang durch Elementaranalyse nicht, zwischen den Formeln C₁₄H₁₂O₅ und C₁₇H₁₄O₆ zu entscheiden. Zwei Hydroxyl- und zwei Methoxylgruppen wurden nachgewiesen. Ein Bericht über spektroskopische Untersuchungen ist in Vorbereitung.

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For Part III see Mikrochim. Acta [Wien]1968, 262.     

A general approach for using a stiff equation solver to integrate a system of partial differential equations

A general approach for using a stiff ordinary differential equation solver to integrate a system of time-dependent partial differential equations in one spacial dimension is described. A computer program based upon the algorithm was written and used to solve nonlinear problems in shock hydrodynamics and hydrology as well as a nonlinear system of ordinary differential equations. The approach is global-implicit and provides an option to the development of specialized computer programs for specific problems of interest. © 1995 John Wiley & Sons, Inc.     

ENTRAINMENT OF HUMAN ORCADIAN RHYTHMS BY LIGHT-DARK CYCLES: A REASSESSMENT

Abstract— Man is the only eukaryotic organism in which it has been reported that the circadian system cannot be entrained to a 24-h period by a simple light-dark (LD) cycle. In this paper, we reexamine the evidence for that claim and demonstrate that there were some fundamental flaws in the experimental design of the previous studies on which this conclusion was based. We report new studies in which we tested the efficacy of LD cycles in entraining the circadian rhythms of human subjects living in isolation from environmental time cues. We found that the cyclic alternation of light and dark, when applied to human subjects in a comparable way to experiments in other species, was an effective entraining agent. Our results and a critical review of the literature indicate that a LD cycle alone can be an effective environmental synchronizer of the human circadian timing system. Other factors, such as the knowledge of time of day, social contacts, the feeding schedule, and the imposed rest-activity schedule may contribute to stable entrainment, although their relative strengths as synchronizers have yet to be determined.     

On the nature of dendrimer cross-linking by ring-closing metathesis

The ring-closing metathesis (RCM) mediated cross-linking of dendrimer 1 and it subunits was examined. Through the combined use of MALDI-MS-TOF, SEC, NMR, and X-ray crystallographic analysis it was shown that the cross-links are formed with the following order of preference: type d >/= type c > type b > type a.     

Molecular imprinting inside dendrimers

Synthetic hosts capable of binding porphyrins have been produced by a mixed-covalent-noncovalent imprinting process wherein a single binding site is created within cross-linked dendrimers. Two synthetic hosts were prepared, using as templates 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(3,5-dihydroxyphenyl)porphyrin. These two templates were esterified with, respectively, fourth- and third-generation Fréchet-type dendrons containing homoallyl end-groups. The resulting tetra- and octadendron macromolecules underwent the ring-closing metathesis reaction using Grubbs' Type I catalyst, RuCl(2)(P(C(6)H(5))(3))(2)(CHCH(2)C(6)H(5)), to give extensive interdendron cross-linking. Hydrolytic removal of the porphyrin cores afforded imprinted hosts whose ability to bind porphyrins with various peripheral substituents was investigated by UV-visible spectrophotometric titrations and size exclusion chromatography. The results indicate a high yield of imprinted sites that show high selectivity for binding of porphyrins capable of making at least four hydrogen bonds, but only a moderate degree of shape selectivity.