Evolution of unoccupied resonance during the synthesis of a silver dimer on Ag(111)

Silver dimers were fabricated on Ag(111) by single-atom manipulation using the tip of a cryogenic scanning tunnelling microscope. An unoccupied electronic resonance was observed to shift toward the Fermi level with decreasing atom-atom distance as monitored by spatially resolved scanning tunnelling spectroscopy. Density functional calculations were used to analyse the experimental observations and revealed that the coupling between the adsorbed atoms is predominantly direct rather than indirect via the Ag(111) substrate.Comment: 9 pages, 3 figure

The Lerch Zeta Function II. Analytic Continuation

This is the second of four papers that study algebraic and analytic structures associated with the Lerch zeta function. In this paper we analytically continue it as a function of three complex variables. We that it is well defined as a multivalued function on the manifold M equal to C^3 with the hyperplanes corresponding to integer values of the two variables a and c removed. We show that it becomes single valued on the maximal abelian cover of M. We compute the monodromy functions describing the multivalued nature of this function on M, and determine various of their properties.Comment: 29 pages, 3 figures; v2 notation changes, homotopy action on lef

SIC-POVMs and the Extended Clifford Group

We describe the structure of the extended Clifford Group (defined to be the group consisting of all operators, unitary and anti-unitary, which normalize the generalized Pauli group (or Weyl-Heisenberg group as it is often called)). We also obtain a number of results concerning the structure of the Clifford Group proper (i.e. the group consisting just of the unitary operators which normalize the generalized Pauli group). We then investigate the action of the extended Clifford group operators on symmetric informationally complete POVMs (or SIC-POVMs) covariant relative to the action of the generalized Pauli group. We show that each of the fiducial vectors which has been constructed so far (including all the vectors constructed numerically by Renes et al) is an eigenvector of one of a special class of order 3 Clifford unitaries. This suggests a strengthening of a conjuecture of Zauner's. We give a complete characterization of the orbits and stability groups in dimensions 2-7. Finally, we show that the problem of constructing fiducial vectors may be expected to simplify in the infinite sequence of dimensions 7, 13, 19, 21, 31,... . We illustrate this point by constructing exact expressions for fiducial vectors in dimensions 7 and 19.Comment: 27 pages. Version 2 contains some additional discussion of Zauner's original conjecture, and an alternative, possibly stronger version of the conjecture in version 1 of this paper; also a few other minor improvement

Unoccupied states of individual silver clusters and chains on Ag(111)

Size-selected silver clusters on Ag(111) were fabricated with the tip of a scanning tunneling microscope. Unoccupied electron resonances give rise to image contrast and spectral features which shift toward the Fermi level with increasing cluster size. Linear assemblies exhibit higher resonance energies than equally sized compact assemblies. Density functional theory calculations reproduce the observed energies and enable an assignment of the resonances to hybridized atomic 5s and 5p orbitals with silver substrate states.Comment: 9 pages, 8 figure

On an Asymptotic Series of Ramanujan

An asymptotic series in Ramanujan's second notebook (Entry 10, Chapter 3) is concerned with the behavior of the expected value of $\phi(X)$ for large $\lambda$ where $X$ is a Poisson random variable with mean $\lambda$ and $\phi$ is a function satisfying certain growth conditions. We generalize this by studying the asymptotics of the expected value of $\phi(X)$ when the distribution of $X$ belongs to a suitable family indexed by a convolution parameter. Examples include the problem of inverse moments for distribution families such as the binomial or the negative binomial.Comment: To appear, Ramanujan

Correlação da emissão diária de metano entérico e características de crescimento e eficiência alimentar de bovinos Nelore.

O objetivo deste trabalho foi avaliar as correlações entre a emissão diária de metano entérico (CH4) e características de crescimento e eficiência alimentar em bovinos Nelore com um ano de idade, previamente avaliados para o consumo alimentar residual (CAR). Foram testados 118 bovinos (56 fêmeas e 62 machos) nascidos em 2010, pertencentes à 30a progênie do rebanho Nelore Tradicional, provenientes do Centro APTA Bovinos de Corte-IZ/SP. O CAR foi estimado como o resíduo da equação de regressão do consumo de matéria seca sobre o peso metabólico e o ganho médio diário em teste pós-desmama de 107 e 112 dias de duração, para machos e fêmeas, respectivamente. Após o teste de desempenho, 46 animais (23 machos e 23 fêmeas) representativos das classes de alto CAR (>média + 0,5 DP; n= 23) e baixo CAR (<média ? 0,5 DP; n= 23), foram utilizados para estimar CH4 por meio da metodologia do gás traçador hexafluoreto de enxofre (SF6) com 7 dias Consecutivos de coleta. A emissão diária de metano está diretamente relacionada ao ganho médio diário e ao consumo de matéria seca. Não há evidências que a emissão diária de metano desses animais tenha relação com o consumo alimentar residual e a conversão alimentar

Light from Cascading Partons in Relativistic Heavy-Ion Collisions

We calculate the production of high energy photons from Compton and annihilation processes as well as fragmentation off quarks in the parton cascade model. The multiple scattering of partons is seen to lead to a substantial production of high energy photons, which rises further when parton multiplication due to final state radiation is included. The photon yield is found to be proportional to the number of collisions among the cascading partons.Comment: revised version: 4 pages, 4 figures, uses REVTEX

Role of elastic scattering in electron dynamics at ordered alkali overlayers on Cu(111)

Scanning tunneling spectroscopy of p(2x2) Cs and Na ordered overlayers on Cu(111) reveals similar line widths of quasi two-dimensional quantum well states despite largely different binding energies. Detailed calculations show that 50% of the line widths are due to electron-phonon scattering while inelastic electron-electron scattering is negligible. A frequently ignored mechanism for ordered structures, i.e., enhanced elastic scattering due to Brillouin zone back folding, contributes the remaining width.Comment: 4 pages, 2 figures, 1 tabl

Emissão de metano entérico e consumo alimentar residual em bovinos Nelore.

O objetivo do trabalho foi avaliar a emissão diária de metano entérico em bovinos Nelore com um ano de idade, previamente avaliados para o consumo alimentar residual (CAR). Foram avaliados 118 animais, machos e fêmeas, nascidos em 2010, provenientes do Centro APTA Bovinos de Corte-IZ/SP. O CAR foi estimado como o resíduo da equação de regressão do consumo de matéria seca (CMS) sobre o peso metabólico e o ganho médio diário (GMD) em teste pós-desmama de 110 dias de duração. Os animais foram classificados por CAR em três grupos: alto CAR (n= 36), médio CAR (n= 42) e baixo CAR (n= 40), levando-se em conta o desvio-padrão da média do CAR de cada sexo. Uma amostra representativa de 46 animais das classes alto e baixo CAR foi usada para avaliar a emissão diária de metano (CH4) por meio da metodologia do gás traçador hexafluoreto de enxofre com 7 dias consecutivos de coleta. Durante a coleta de metano o CMS foi também obtido. Apesar da diferença do CMS dos animais das duas classes de CAR, não houve diferença significativa na CH4. Quando a CH4 foi expressa em relação ao GMD, houve diferença significativa entre os animais mais e menos eficientes. Os animais mais eficientes (baixo CAR) emitem menos CH4 por kg de ganho de peso que os animais menos eficientes (alto CAR)

The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-convective Wind Event

Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses