Observational tests for oscillating expansion rate of the Universe

We investigate the observational constraints on the oscillating scalar field model using data from type Ia supernovae, cosmic microwave background anisotropies, and baryon acoustic oscillations. According to a Fourier analysis, the galaxy number count $N$ from redshift $z$ data indicates that galaxies have preferred periodic redshift spacings. We fix the mass of the scalar field as $m_\phi=3.2\times 10^{-31}h$ ${\rm eV}$ such that the scalar field model can account for the redshift spacings, and we constrain the other basic parameters by comparing the model with accurate observational data. We obtain the following constraints: $\Omega_{m,0}=0.28\pm 0.03$ (95% C.L.), $\Omega_{\phi,0} -158$ (95% C.L.) (in the range $\xi \le 0$). The best fit values of the energy density parameter of the scalar field and the coupling constant are $\Omega_{\phi,0}= 0.01$ and $\xi= -25$, respectively. The value of $\Omega_{\phi,0}$ is close to but not equal to $0$. Hence, in the scalar field model, the amplitude of the galaxy number count cannot be large. However, because the best fit values of $\Omega_{\phi,0}$ and $\xi$ are not $0$, the scalar field model has the possibility of accounting for the periodic structure in the $N$--$z$ relation of galaxies. The variation of the effective gravitational constant in the scalar field model is not inconsistent with the bound from observation.Comment: 9 pages, 11 figures, 1 table, Accepted for publication in Physical Review

Janus within Janus

We found a simple and interesting generalization of the non-supersymmetric Janus solution in type IIB string theory. The Janus solution can be thought of as a thick AdS_d-sliced domain wall in AdS_{d+1} space. It turns out that the AdS_d-sliced domain wall can support its own AdS_{d-1}-sliced domain wall within it. Indeed this pattern persists further until it reaches the AdS_2-slice of the domain wall within self-similar AdS_{p (2<p\le d)}-sliced domain walls. In other words the solution represents a sequence of little Janus nested in the interface of the parent Janus according to a remarkably simple ``nesting'' rule. Via the AdS/CFT duality, the dual gauge theory description is in general an interface CFT of higher codimensions.Comment: 15 pages, 6 figures, v2 references added. v3 eq.(3.33) correcte

CGC, Hydrodynamics, and the Parton Energy Loss

Hadron spectra in Au+Au collisions at RHIC are calculated by hydrodynamics with initial conditions from the Color Glass Condensate (CGC). Minijet components with parton energy loss in medium are also taken into account by using parton density obtained from hydrodynamical simulations. We found that CGC provides a good initial condition for hydrodynamics in Au+Au collisions at RHIC.Comment: Quark Matter 2004 contribution, 4 pages, 2 figure

Flounder metamorphosis: its regulation by various hormones

The elongation and shortening of the flounder fin rays during its metamorphosis may be parallel to the appearance and resorption of the tadpole tail during amphibian metamorphosis. The dorsal fin rays of the Japanese flounder (Paralichthys olivaceus) elongate during the time when thyroid hormone levels are low and are resorbed during climax of metamorphosis when thyroid levels are elevated. Using an in vitro system for culture of isolated flounder fin rays, we examined how various hormones affect the process of resorption. Both T4 and T3 directly stimulated fin ray shortening, T3 being more potent than T4. Other hormones did not directly affect the resorption process but modified the tissue's response to thyroid hormones. Cortisol enhanced the stimulatory effects of both T4 and T3. On the other hand, estradiol and testosterone were inhibitory. Ovine prolactin (oPRL) also diminished the effect of T3 while ovine growth hormone (oGH) was without effect. Similar observations were observed from the in vivo studies. Thyroid hormone levels, especially T4, were low during premetamorphosis, increased during prometamorphosis, to peak levels during metamorphic climax, and declined in the juveniles. The changes in whole body concentrations of Cortisol paralleled the changes in thyroid hormone concentrations. On the other hand, whole body estradiol and testosterone concentrations did not show significant change and remained low throughout the larval period. The expression of GH and PRLmRNA, as assessed by in situ hybridization using cDNA for flounder PRL and GH also increased during the metamorphosis. However, the increase in the expression of GH and PRL genes was observed later than the increases in tissue levels of thyroid hormones and Cortisol. At late climax, the flounder larvae have undergone considerable transformation, presumably triggered by both hormones, hence the increase in PRL could hardly be antimetamorphic but may have other physiological implications

ISWI remodeling complexes in Xenopus egg extracts: Identification as major chromosomal components that are regulated by INCENP-aurora B

We previously characterized major components of mitotic chromosomes assembled in Xenopus laevis egg extracts and collectively referred to them as Xenopuschromosome–associated polypeptides (XCAPs). They included five subunits of the condensin complex essential for chromosome condensation. In an effort to identify novel proteins involved in this process, we have isolated XCAP-F and found it to be theXenopus ortholog of ISWI, a chromatin remodeling ATPase. ISWI exists in two major complexes in Xenopus egg extracts. The first complex contains ACF1 and two low-molecular-weight subunits, most likely corresponding to Xenopus CHRAC. The second complex is a novel one that contains theXenopus ortholog of the human Williams syndrome transcription factor (WSTF). In the absence of the ISWI complexes, the deposition of histones onto DNA is apparently normal, but the spacing of nucleosomes is greatly disturbed. Despite the poor spacing of nucleosomes, ISWI depletion has little effect on DNA replication, chromosome condensation or sister chromatid cohesion in the cell-free extracts. The association of ISWI with chromatin is cell cycle regulated and is under the control of the INCENP-aurora B kinase complex that phosphorylates histone H3 during mitosis. Apparently contradictory to the generally accepted model, we find that neither chromosome condensation nor chromosomal targeting of condensin is compromised when H3 phosphorylation is drastically reduced by depletion of INCENP-aurora B

Situação da Produção de Batata-semente no Brasil.

O Brasil é um país muito grande em extensão territorial e diversidade climática e possibilita a produção de batata (semente e consumo) durante todos os dias do ano, portanto para se ter um retrato mais fiel da produção de sementes é necessário apresentar a área e produção de batata consumo no país, conforme mostra a Tabela 1

Elliptic flow of thermal dileptons as a probe of QCD matter

We study the variation of elliptic flow of thermal dileptons with transverse momentum and invariant mass of the pairs for Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The dilepton productions from quark gluon plasma (QGP) and hot hadrons have been considered including the spectral change of light vector mesons in the thermal bath. The space time evolution has been carried out within the frame work of 2+1 dimensional ideal hydrodynamics with lattice+hadron resonance gas equation of state. We find that a judicious selection of invariant mass(M) and transverse momentum (p_T) windows can be used to extract the collective properties of quark matter, hadronic matter and also get a distinct signature of medium effects on vector mesons. Our results indicate a reduction of elliptic flow (v_2) for M beyond phi mass, which if observed experimentally would give the measure of v_2 of the partonic phase.Comment: To appear in Phys. Rev. C (Rapid Comm.

Situação atual do Sistema de Certificação de Batata-semente no Brasil e análise dos aspectos fitossanitários para o intercâmbio internacional de Batata-semente.

O sistema de certificação de batata-semente no Brasil houve início em 1973 com a implantação da classe certificada, utilizando sementes básicas importadas da Europa, mas com o início da produção de batata-semente básica no país. Em 1982 houve modificação da legislação com a implantação das classes básica, registrada e certificada subclasses A e B, e finalmente com aumento do volume de produção de sementes básicas, inclusive por empresas privadas que utilizam a biotecnologia no processo de produção de sementes