Evidence for Gluon Recombination in Deep Inelastic Scattering

The pomeron structure function is extracted from the latest H1 data and are subject to a QCD analysis. The result shows evidence for gluon recombination.Comment: 8 pages, 5 figure

Geometry of the Prytz Planimeter

The Prytz planimeter is a simple example of a system governed by a non-holonomic constraint. It is unique among planimeters in that it measures something more subtle than area, combining the area, centroid and other moments of the region being measured, with weights depending on the length of the planimeter. As a tool for measuring area, it is most accurate for regions that are small relative to its length. The configuration space of the planimeter is a non-principal circle bundle acted on by SU(1,1), (isom. to SL(2,R)). The motion of the planimeter is realized as parallel translation for a connection on this bundle and for a connection on a principal SU(1,1)-bundle. The holonomy group is SU(1,1). As a consequence, the planimeter is an example of a system with a phase shift on the circle that is not a simple rotation. There is a qualitative difference in the holonomy when tracing large regions as opposed to small ones. Generic elements of SU(1,1) act on S^1 with two fixed points or with no fixed points. When tracing small regions, the holonomy acts without fixed points. Menzin's conjecture states (roughly) that if a planimeter of length L traces the boundary of a region with area A > pi L^2, then it exhibits an asymptotic behavior and the holonomy acts with two fixed points, one attracting and one repelling. This is obvious if the region is a disk, and intuitively plausible if the region is convex and A >> pi L^2. A proof of this conjecture is given for a special case, and the conjecture is shown to imply the isoperimetric inequality.Comment: AmS-TeX, 23 pages, 12 figures in 2 *.gif files. To appear in Reports on Mathematical Physics. Part of proceedings of Workshop on Non-holonomic Constraints in Dynamics, Univ. of Calgary, Aug. 199

Automated approaches for band gap mapping in STEM-EELS

Band gap variations in thin film structures, across grain boundaries, and in embedded nanoparticles are of increasing interest in the materials science community. As many common experimental techniques for measuring band gaps do not have the spatial resolution needed to observe these variations directly, probe-corrected Scanning Transmission Electron Microscope (STEM) with monochromated Electron Energy-Loss Spectroscopy (EELS) is a promising method for studying band gaps of such features. However, extraction of band gaps from EELS data sets usually requires heavy user involvement, and makes the analysis of large data sets challenging. Here we develop and present methods for automated extraction of band gap maps from large STEM-EELS data sets with high spatial resolution while preserving high accuracy and precision

Transition metal d-band occupancy in skutterudites studied by electron energy-loss spectroscopy

The transition-metal 3d occupancy of a series of thermoelectric skutterudites is investigated using electron energy-loss spectroscopy. We find that bonding causes an emptying of the 3d states in the binary skutterudites CoP3, CoAs3, CoSb3, and NiP3, while compared to the pure Fe the 3d occupancy in LaFe4P12 is significantly increased, consistent with the idea that each interstitial La atom (rattler) donates three electrons to compensate for missing valence electron of Fe as compared to Co. These experimental results are in agreement with previous models suggesting a predominantly covalent bonding between transition metal and pnictogen atoms in skutterudites, and provide evidence of charge transfer from La to the Fe-P complex in LaFe4P12

Accurate determination of domain boundary orientation in LaNbO4

The orientation relationship between ferroelastic domains in LaNbO4 (with 0.5 at.% Sr) is studied by selected area electron diffraction and high-resolution electron microscopy. At room temperature the domains are related through a simple rotation of approximately 95 degrees about the monoclinic [0 1 0] axis, and the interface between two adjacent domains is highly ordered. The domain boundary is found to be the (2 0 5.10)/(5.10 0 2) planes of the two domains, in excellent agreement with our theoretical predictions. This orientation differs considerably from that predicted by more elaborate ferroelastic theory

Florae Fennicae breviarium, dissertationibus academicis absolvendum, quarum sextam, venia amplissimae facultatis philosophicae Aboënsis, publicae censurae subjiciunt auctor, Laurentius Johannes Prytz, medicinae & philosophiae doctor, atque respondens Isaacus Reginaldus Eneberg, Borea-Fenno. In auditorio medico, die XII Maji MDCCCXXI, horis post meridiem consvetis.

Painovuosi nimekkeestä.Arkit: 1 arkintunnukseton lehti, L-M4. - S. [2] tyhjä.Jatko ilmestynyt julkaisussa: Notiser ur Sällskapets pro Fauna et Flora Fennica förhandlingar. 10 (1862)

Reduction of lattice thermal conductivity from planar faults in the layered Zintl compound SrZnSb_2

The layered Zintl compound SrZnSb_2 is investigated using transmission electron microscopy (TEM) to understand the low lattice thermal conductivity. The material displays out-of-phase boundaries with a spacing from 100 down to 2 nm. Density functional theory calculations confirm that the TEM-derived defect structure is energetically reasonable. The impact of these defects on phonon scattering is analyzed within the Debye–Callaway model, which reveals a significant reduction in the acoustic phonon mean free path. This enhancement in phonon scattering leads to an ~30% reduction in lattice thermal conductivity at 300 K

How to measure the intercept of the BFKL pomeron at HERA

Determination of the intercept of the BFKL pomeron is one of the pressing issues in the high energy physics. Earlier we have shown that, at the dipole size $r=r_{\Delta}=(0.1-0.2)$f, the dipole cross section $\sigma(x,r)$ which is a solution of the generalized BFKL equation, exhibits a precocious asymptotic behavior \sigma(x,r)\propto \left({1\over x}\right)^{\Delta_{\Pom}}. In this paper we discuss how measuring $F_{L}(x,Q^{2})$ and $\partial F_{T}(x,Q^{2})/\partial \log Q^{2}$ at $Q^{2}= (10-40)$GeV$^{2}$ and $Q^{2}=(2-10)$GeV$^{2}$, respectively, one can probe $\sigma(x,r_{\Delta})$ and directly determine the intercept \Delta_{\Pom} of the BFKL pomeron in the HERA experiments.Comment: 10 pages, 2 figures upon the request from [email protected], Juelich preprint KFA-IKP(Th)-1994-10, 28 February 199

Valence band study of thermoelectric Zintl-phase SrZn_2Sb_2 and YbZn_2Sb_2: X-ray photoelectron spectroscopy and density functional theory

The electronic structure of SrZn_2Sb_2 and YbZn_2Sb_2 is investigated using density functional theory and high-resolution x-ray photoemission spectroscopy. Both traditional Perdew-Burke-Ernzerhof and state-of-the-art hybrid Heyd-Scuseria-Ernzerhof functionals have been employed to highlight the importance of proper treatment of exchange-dependent Zn  3d states, Yb 4f states, and band gaps. The role of spin-orbit corrections in light of first-principles transport calculations are discussed and previous claims of Yb^(3+) valence are investigated with the assistance of photoelectron as well as scanning and transmission electron microscopy