376 research outputs found
Gauge fields in a string-cigar braneworld
In this work we investigate the properties of an Abelian gauge vector field
in a thin and in a smoothed string-like braneworld, the so-called string-cigar
model. This thick brane scenario satisfies the regularity conditions and it can
be regarded as an interior and exterior string-like solution. The source
undergoes a geometric Ricci flow which is connected to a variation of the bulk
cosmological constant. The Ricci flow changes the width and amplitude of the
massless mode at the brane core and recover the usual thin string-like behavior
at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum
for both the thin brane and the string-cigar. It turns out that both models
exhibit a mass gap between the massless and the massive modes and between the
high and the low mass regimes. The KK modes are smooth near the brane and their
amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger
potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was
improved. Numerical analysis was adapted to the conventional notation on
Kaluza-Klein number. Some graphics were modified for considering other
notation. Results unchanged. References added. Corrected typos. 17 pages. 6
figures. To match version to appears in Physics Letters
Gravity localization on hybrid branes
This work deals with gravity localization on codimension-1 brane worlds
engendered by compacton-like kinks, the so-called hybrid branes. In such
scenarios, the thin brane behaviour is manifested when the extra dimension is
outside the compact domain, where the energy density is non-trivial, instead of
asymptotically as in the usual thick brane models. The zero mode is trapped in
the brane, as required. The massive modes, although are not localized in the
brane, have important phenomenological implications such as corrections to the
Newton's law. We study such corrections in the usual thick domain wall and in
the hybrid brane scenarios. By means of suitable numerical methods, we attain
the mass spectrum for the graviton and the corresponding wavefunctions. The
spectra possess the usual linearly increasing behaviour from the Kaluza-Klein
theories. Further, we show that the 4D gravitational force is slightly
increased at short distances. The first eigenstate contributes highly for the
correction to the Newton's law. The subsequent normalized solutions have
diminishing contributions. Moreover, we find out that the phenomenology of the
hybrid brane is not different from the usual thick domain wall. The use of
numerical techniques for solving the equations of the massive modes is useful
for matching possible phenomenological measurements in the gravitational law as
a probe to warped extra dimensions.Comment: 15 pages, 11 figure
A smoothed string-like braneworld in six dimensions
We propose here a static and axisymmetric braneworld in six dimensions as a
string-like model extension. For a subtle warp function, this scenario provides
near brane corrections. By varying the bulk cosmological constant, we obtain a
source which passes through different phases. The solution is defined both for
the interior as for the exterior of the string and satisfies the weak energy
condition. Smooth gravitational massless mode is localized on the brane which
core is displaced from the origin. In contrast to the thin string model, the
massive solutions have high amplitude near the brane. By means of an analogue
quantum potential analysis, we show that s-waves gravitational Kaluza-Klein
modes are permissible as resonant states.Comment: 8 pages, 10 figure
Doppler imaging of the planetary debris disc at the white dwarf SDSS J122859.93+104032.9
Debris discs which orbit white dwarfs are signatures of remnant planetary systems. We present 12 yr of optical spectroscopy of the metal-polluted white dwarf SDSS J1228+1040, which shows a steady variation in the morphology of the 8600 Å Ca II triplet line profiles from the gaseous component of its debris disc. We identify additional emission lines of O I, Mg I, Mg II, Fe II and Ca II in the deep co-added spectra. These emission features (including Ca H & K) exhibit a wide range in strength and morphology with respect to each other and to the Ca II triplet, indicating different intensity distributions of these ionic species within the disc. Using Doppler tomography, we show that the evolution of the Ca II triplet profile can be interpreted as the precession of a fixed emission pattern with a period in the range 24–30 yr. The Ca II line profiles vary on time-scales that are broadly consistent with general relativistic precession of the debris disc
Avaliação de técnicas biomoleculares em amostras de sangue e ovócitos de fêmeas infectadas com vírus da Artrite Encefalite Caprina.
Detecção do vírus da Artrite Encefalite Caprina por nested PCR e nested RT-PCR em ovócitos e fluido uterino.
Resumo: A Artrite Encefalite Caprina (CAE) é uma enfermidade infectocontagiosa causada por um vírus pertencente ao gênero lentivírus, denominado de vírus da Artrite Encefalite Caprina (CAEV). O CAEV é encontrado em vários tecidos, como o nervoso, o pulmonar, o da glândula mamária e do trato genital masculino e feminino. Desta forma, objetivou-se com este trabalho identificar a presença do CAEV, pelas técnicas de diagnóstico moleculares, em ovócitos e fluido uterino, visando avaliar a possibilidade de transmissão do CAEV pela reprodução. Foram selecionadas 13 cabras comprovadamente infectadas, as quais foram submetidas à eutanásia para coleta do aparelho reprodutor, aspiração do fluido uterino e dissecção dos ovários para coleta de ovócitos. Para identificação do CAEV nas amostras coletadas, na forma de provírus e na forma livre, foram realizadas as técnicas de PCRn e RT-PCRn, respectivamente. Observaram-se que 53,8% dos ovócitos foram positivos à técnica de RT-PCRn, enquanto apenas 9,1% foram positivos à PCRn. A técnica de RT-PCRn também identificou o vírus no fluido uterino de 46,1% das fêmeas testadas. Embora as 13 cabras em experimento fossem portadoras do CAEV, 30,8% apresentaram resultados negativos na PCRn e RT-PCRn em todas as amostras analisadas (ovócito e fluido uterino). Conclui-se que a PCRn e a RT-PCRn podem ser utilizadas no diagnóstico da CAE tendo os ovócitos e o fluido uterino como materiais de análise, e que a presença do CAEV nestes materiais aponta para o risco da transmissão do CAEV através das tecnologias reprodutivas aplicadas às fêmeas. [Caprine Arthritis Encephalitis virus is detected in oocytes and uterine fluid by nested PCR and nested RT-PCR]. Abstract: Caprine arthritis-encephalitis (CAE) is an infectious disease caused by the caprine arthritis-encephalitis virus (CAEV), belonging to the lentivirus genus. The presence of the virus has been observed in the nervous system, respiratory tract and mammary gland, and also in the male and female genital tract. The objective of this study is to identify the virus in oocyte and uterine fluid of infected goats by molecular diagnostic techniques, in order to assess the possibility of CAEV transmission with reproduction. Thirteen infected goats were selected and submitted to euthanasia for the collection of the reproductive system, aspiration of the uterine fluid and dissection of ovaries for oocyte collection. In order to identify the CAEV in the collected material, in the protovirus and free forms, it was submitted to the nRT-PCR and nPCR techniques, respectively. As a result, it was observed that 53.8% of oocytes were positive to nRT-PCR, while only 9.1% were positive to nPCR. The nRT-PCR also identified the virus in the uterine fluid of 46.1% of the tested females. Even though the 13 goats had CAEV, 30.8% presented negative results in nPCR and nRTPCR in all of the analyzed samples (oocyte and uterine fluid). This work concludes that nRT-PCR and nPCR can be used in the diagnosis of CAE for the analysis with oocytes and uterine fluid, and that the presence of CAEV in these materials points out to the risk of CAEV transmission through reproductive technologies used in females
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