Five-Dimensional QED, Muon Pair Production and Correction to the Coulomb Potential

We consider QED in five dimensions in a configuration where matter is localized on a 3-brane while foton propagates in the bulk. The idea is to investigate the effects of the Kaluza-Klein modes of the photon in the relativistic regime, but in low energy, and in the nonrelativistic regime. In the relativistic regime, we calculate the cross section for the reaction $e^+ + e^- \to \mu^+ + \mu^-$. We compare our theoretical result with a precise measurement of this cross section at $\sqrt{s}=57.77$ GeV. As result, we extract a lower bound on the size of the extra dimension. In the nonrelativistic regime, we derive the contribution for the Coulomb potential due to the whole tower of the Kaluza-Klein excited modes of the photon. We use the modified potential to calculate the Rutherford scattering differential cross section.Comment: minor changes, three new refs. added, to appear in IJMP

Proper motions of ROSAT discovered isolated neutron stars measured with Chandra: First X-ray measurement of the large proper motion of RX J1308.6+2127/RBS 1223

The unprecedented spatial resolution of the Chandra observatory opens the possibility to detect with relatively high accuracy proper motions at X-ray wavelengths. We have conducted an astrometric study of three of the "Magnificent Seven", the thermally emitting radio quiet isolated neutron stars (INSs) discovered by ROSAT. These three INSs (RX J0420.0-5022, RX J0806.4-4123 and RX J1308.6+2127/RBS 1223) either lack an optical counterpart or have one too faint to be used for astrometric purposes. We obtained ACIS observations 3 to 5 years apart to constrain or measure the displacement of the sources on the X-ray sky using as reference the background of extragalactic or remote galactic X-ray sources. Upper limits of 138 mas/yr and 76 mas/yr on the proper motion of RX J0420.0-5022 and RX J0806.4-4123, respectively, have already been presented in Motch et al. (2007). Here we report the very significant measurement (~ 10 sigma) of the proper motion of the third INS of our program, RX J1308.6+2127/RBS1223. Comparing observations obtained in 2002 and 2007 reveals a displacement of 1.1 arcsec implying a yearly proper motion of 223 mas, the second fastest measured for the ROSAT discovered INSs. The source is rapidly moving away from the galactic plane at a speed which precludes any significant accretion of matter from the interstellar medium. Its transverse velocity of ~ 740 (d/700pc) km/s might be the largest of the "Magnificent Seven" and among the fastest recorded for neutron stars. RX J1308.6+2127/RBS1223 is thus a young high velocity cooling neutron star. The source may have its origin in the closest part of the Scutum OB2 association about 0.8 Myr ago, an age consistent with that expected from cooling curves, but significantly younger than inferred from pulse timing measurements (1.5 Myr).Comment: 3 pages, 2 figures, proceedings of the conference "40 Years of Pulsars", 12-17 August 2007, Montreal, Canad

Comment on ``Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions''

We point out that if the majoron-like scheme is implemented within a 331 model, there must exist at least three different mass scales for the scalar vacuum expectation values in the model.Comment: 4 pages, no figures, Revtex. To be published in Physical Review

On the benefits of speech and touch interaction with communication services for mobility impaired users

Although technology for communication has evolved tremendously over the past decades, mobility impaired individuals still face many difficulties interacting with communication services, either due to HCI issues or intrinsic design problems with the services. In this paper we present the results of a usability study, conducted with a group of five mobility impaired users, comprising paraplegic and quadriplegic individuals. The study participants carried out a set of tasks with a multimodal (speech, touch, gesture, keyboard and mouse) and multiplatform (mobile, desktop) prototype, offering an integrated access to communication and entertainment services, such as email, agenda, conferencing and social media. The prototype was designed to take into account the requirements captured from these users, with the objective of evaluating if the use of multimodal interfaces for communication and social media services, could improve the interaction with such services. Our study revealed that a multimodal prototype system, offering natural interaction modalities, especially supporting speech and touch, can in fact improve access to the presented services, contributing to a better social inclusion of mobility impaired individuals.info:eu-repo/semantics/acceptedVersio

Qualidade de mudas de melão produzidas em diferentes substratos.

The aim of this paper was to evaluate the development of melon seedlings grown in different substrates. The experiment was carried out in a greenhouse covered with 25% screen, at the Department of Technology and Social Sciences -DTCS of the University of the State of Bahia / UNEB, Juazeiro-BA, from July to August 2005. It was used a completely randomized experimental design with six treatments and four replications, each one consisted of 50 seedlings. The treatments composed of the substrates: Plantmax HT©; soil; sterilized soil; sugarcane residue; sugarcane residue + soil (1:1) and sugarcane residue + urea. Polystyrene trays of 200 cells were used as containers, where seeds of the AF882 melon cultivar. We sowed at 1 cm depth, using one seed per cell. The emergence percentage, average emergence time and average emergence velocity were determined. Fourteen days after sowing were evaluated seedling height, shoot and toot fresh and dry masses leaf area and chlorophyll content. The results allow one to conclude that the commercial substrate Plantmax HT© and the sterilized soil were those that provided the best melon seedlings formation

Influencia da embalagem e condicoes de armazenamento na longevidade de sementes florestais.

Permite conhecer as condicoes de embalagens de armazenamento que proporcionem maior longevidade das sementes de angico (Anadenanthera macrocarpa (Benth) Brenan, Pau d'arco (Tabebuia impetiginosa Mart) e imbirucu (Pseudobombax simpliciflolium A. Robyns)

Biology of the iberian chub (Squalius carolitertii) in an atlantic-type stream (river Lima basin-north Portugal). A preliminary approach

The iberian chub (Squalius carolitertii) is an endemic species whose biology is yet largely unknown and which is catalogued as being endangered. Therefore more information about its biology is essential to develop appropriate management strategies. The Estorâos River population has been studied from December 1995 to March 2002 through regular electro-fishing surveys. Additionally, a fish trap installed in the river from November 2001 to July 2002 allowed for the collection of information on population movements and reproduction. The results revealed some fluctuations in the density estimates, though the Squalius carolitertii population in the Estorâos River is quite low. Six age classes (0+ to 5+) were identified. Iberian chub growth is isometric and can reach a final length of 33.5 cm. Sexual dimorphism is evident, with males maturing earlier and at smaller sizes. An increase of the Iberian chub movements was detected from middle April onwards. These movements were related to the beginning of the reproductive period and were mainly correlated with the rise of water temperature. Our results indicate that the population characteristics do not differ substantially from those of other endemic chub populations in the Iberic peninsula.El bordallo (Squalius carolitertii) es una especie cuya biología es en gran parte desconocida y que está catalogada en peligro de extinción. El estudio de su biología es importante para la gestión de sus poblaciones y de su hábitat. La población del río Estorâos (Cuenca del río Límia) ha sido estudiada de Diciembre de 1995 a Marzo de 2002 mediante muestreos con pesca eléctrica. Un sistema de redes utilizado de Noviembre de 2001 a Julio de 2002 permitió la obtención de información sobre los movimientos y parámetros reproductivos de la población. Los datos indican fluctuaciones de la densidad, a pesar de la población presentar valores muy bajos. Seis clases de edad (0+ a 5+) han sido identificadas. El crecimiento de Squalius carolitertii es isométrico y puede llegar a una talla final de 33,5 cm. El dimorfismo sexual es evidente y los machos maduran más temprano y con tallas inferiores a de las hembras. Un creciente de movimientos del bordallo ha sido encontrado a mediados del mes de Abril, lo que está de acuerdo con la fecha del período reproductivo y también con el incremento de la temperatura del agua. Nuestros datos indican que esta población no es muy distinta de otras poblaciones de bordallos endémicos de la península Ibérica

Pecuária de precisão: pesquisas em saúde e comportamento alimentar.

bitstream/item/126300/1/Cnpgl-2014-Leite-Integral-Pecuaria.pd