Antimatter,by F. Close

While high resolution electron microscopy has been in use for many years, with steadily improving image resolution, most modern microscopes can provide complementary information on the chemical composition of very small volumes of material. This advance is very important and enormously extends the range of practical applications for the electron microscope. This review describes the basic principles and techniques of high resolution imaging and analysis, in both the conventional and scanning electron microscope, noting in each case the resolution that may be achieved.     

Measurement of the absolute branching fraction of Ds+ --> tau+ nutau decay

Using a sample of tagged D(s)(+) decays collected near the D(s)(*+/-)D(s)(-/+) peak production energy in e(+)e(-) collisions with the CLEO-c detector, we study the leptonic decay D(s)(+)-->tau(+)nu(tau) via the decay channel tau(+)-->e(+)nu(e)nu(tau). We measure B(D(s)(+)-->tau(+)nu(tau))=(6.17+/-0.71+/-0.34)%, where the first error is statistical and the second systematic. Combining this result with our measurements of D(s)(+)-->mu(+)nu(mu) and D(s)(+)-->tau(+)nu(tau) (via tau(+)-->pi(+)nu(tau)), we determine f(D(s))=(274+/-10+/-5) MeV.     

Abelian functions for cyclic trigonal curves of genus 4

We discuss the theory of generalized Weierstrass σ$\sigma$ and ℘$\wp$-functions defined on a trigonal curve of genus 4, following earlier work on the genus 3 case. The specific example of the “purely trigonal” (or “cyclic trigonal”) curve y³=x⁵+_λ4x⁴+_λ3x³+_λ2x²+_λ1x+_λ0$y^3=x^5+{\lambda }_4{x}^4+{\lambda }_3{x}^3+{\lambda }_2{x}^2+{\lambda }_{1}x+{\lambda }_0$ is discussed in detail, including a list of some of the associated partial differential equations satisfied by the ℘$\wp$-functions, and the derivation of addition formulae.     

Alignment of guest–host liquid crystals with polarized laser light

Abstract

Surface-mediated alignment of nematic liquid crystals with polarized laser light was reported recently [1]. In this communication we describe the alignment of a guest–host liquid crystal medium with polarized laser light. Liquid crystals in the illuminated region orient perpendicular to the direction of the laser polarization and remain aligned in the absence of laser radiation. The liquid crystals can be reoriented again by subsequent illumination. The kinetic feature of this surface-mediated liquid crystal orientation is characterized by the presence of coexisting liquid crystal regions of directors pointing away from the initial alignment.     

Reduction of antimony(V) by dithiophosphinates and the crystal structure of dimeric diphenylantimony(III) dimethyldithiophosphinate

Reactions between three diorganodithiophosphinates and diphenylantimony(V) bromide oxide (SbPh₂OBr)₂, led to antimony reduction while dithiophosphinate oxidation followed a complex path varying in detail with the nature of the organic groups on dithiophosphinate. Antimony(III) dithiophosphinates, SbPh₂(S₂PR₂) where R = Me, Et and Ph, have been isolated and characterised and an X-ray structure determination for the methyl derivative shows weakly associated dimers in the solid state, intermediate between those in (SbPh₂S₂PPh₂)₂ and [Sb(4-MeC₆H₄)₂S₂PEt]₂.     

Finite partitions of spheres

Let Sⁿ be the unit sphere in E^{n + 1}; an (n ? 1)-sphere in Sⁿ is an intersection of Sⁿ with a hyperplane. A theorem is proved on colorings of sphere which implies the Proposition: If B is an m-coloring of S², for m ? 6, B4-colors some 1-sphere. If B is an m-coloring of S³, m ? 8; B 5-colors some 2-sphere.     

Changing Teacher Behavior Through Staff Development: Implementing the Teaching and Content Standards in Science

For the last five years, the Center for Precollege Programs of the New Jersey Institute of Technology has operated the Urban Elementary Outreach Program, a staff development program intended to bring improved math and science education to the elementary schools of Newark, New Jersey. Teachers in urban settings have been hampered in their efforts to provide enriching, student-centered and constructivist science and math teaching ( Huinker, 1996 ). The Outreach Program has attempted to provide teachers with sustained support through training and direct classroom assistance in an effort to develop a sense of self-efficacy ( Bandura, 1982 ) in relation to desired teaching and student behaviors that are part of a standards-based learning experience. Traditional training approaches for teachers are supplemented by weekly classroom visits by graduate assistants, who both model standards-based science teaching and assist the teacher in assuming effective instructional methods. The combination of workshops, orientations, newsletters, and weekly classroom visits make up a staff development program of two years in duration for teacher participants. Through this intensive program, we intend to change teaching behaviors in the many complex ways identified in the National Science Education Standards.     

Laser heating: an analytical approach to the theory

The theory of pulsed and scanned laser beams is developed and the results are shown to agree with similar analyses by other authors. A new expression, however, for the temperature rise caused by a very small laser spot agrees well with recent experiments.     

Einstein metrics onS 3,R 3 andR 4 bundles

Starting from a 4n-dimensional quaternionic Kähler base space, we construct metrics of cohomogeneity one in (4n+3) dimensions whose level surfaces are theS ² bundle space of almost complex structures on the base manifold. We derive the conditions on the metric functions that follow from imposing the Einstein equation, and obtain solutions both for compact and non-compact (4n+3)-dimensional spaces. Included in the non-compact solutions are two Ricci-flat 7-dimensional metrics withG ₂ holonomy. We also discuss two other Ricci-flat solutions, one on theR ⁴ bundle overS ³ and the other on anR ⁴ bundle overS ⁴. These haveG ₂ and Spin(7) holonomy respectively.     

Monitoring of odorant components in British natural Gas

Summary The individual sulphur compounds that make up the odorant in natural gas are analysed with purpose-made equipment, using chromatographic separation and a flame photometric detector. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984