Especificidade na infecção de raízes por Azospirillum spp em plantas com via fotossintética C3 e C4

The occurence of Azospirillum brasilense and A. lipoferum and their nir+ and nir- variants was determined in soil and in non-sterilized and sterilized roots of the C3 cereals wheat, rye, barley and oat and of several C4 grasses. The C3 cereals were planted in pots with red-yellow podzolic soil and examined at two growth stages. The C4 forage grasses were collected in fields where the respective species were predominant. In all soils A. brasilense seemed to predominate. The proportion of A. brasilense nir- was above 80% in all C3 cereals when surface sterilized roots were examined. Azospirillum isolates from surface sterilized roots of C4 grasses were predominantly A. lipoferum but only in some species (Panicum maximum, Sorghum vulgare and Brachiaria sp) the nir- forms predominated. A weed belonging to Cyperaceae (Cyperus rotundus) was also infected by A. lipoferum nir- as in the case of other C4 grasses. The only exception among the C4 Gramineae was sugar cane which seemed to behave like the C3 cereals, and all 24 isolates from surface sterilized roots were A. brasilense nir-.Resultados anteriores sobre a especificidade hospedeira na infecção de gramíneas com Azospirillum spp foram confirmados no presente trabalho, com maior número de espécies. No solo ocorreram as duas espécies de Azospirillum - A. brasilense e A. lipoferum - e, ainda estirpes denitrificantes (nir+) e não-denitrificantes (ni-). Os isolamentos de raízes esterilizadas de cereais de clima temperado com via fotossintética C3 (trigo, cevada, aveia e centeio), foram predominantemente da espécie A. brasilense; e os de raízes esterilizadas de gramíneas tropicais com via C4 foram predominantemente da espécie A. lipoferum. Em ambos os casos parece que as plantas, especialmente as C3, apresentam seletividade para estirpes não denitrificantes. A única exceção nestas observações foi a cana-de-açúcar, que se comportou como os cereais temperados. Por outro lado, a tiririca, uma Cyperacea com via C4, foi infectada por A. lipoferum, como as gramíneas com via C4

Quantifying the levitation picture of extended states in lattice models

The behavior of extended states is quantitatively analyzed for two dimensional lattice models. A levitation picture is established for both white-noise and correlated disorder potentials. In a continuum limit window of the lattice models we find simple quantitative expressions for the extended states levitation, suggesting an underlying universal behavior. On the other hand, these results point out that the Quantum Hall phase diagrams may be disorder dependent.Comment: 5 pages, submitted to PR

Scalar perturbations in conformal rolling scenario with intermediate stage

Scalar cosmological perturbations with nearly flat power spectrum may originate from perturbations of the phase of a scalar field conformally coupled to gravity and rolling down negative quartic potential. We consider a version of this scenario whose specific property is a long intermediate stage between the end of conformal rolling and horizon exit of the phase perturbations. Such a stage is natural, e.g., in cosmologies with ekpyrosis or genesis. Its existence results in small negative scalar tilt, statistical anisotropy of all even multipoles starting from quardupole of general structure (in contrast to the usually discussed single quadrupole of special type) and non-Gaussianity of a peculiar form.Comment: 35 pages, 1 figure. Journal version. Discussion of the range of relevant momentum scales and bounds on parameters adde

Defining the genomic signature of the parous breast.

ABSTRACT: BACKGROUND: It is accepted that a woman's lifetime risk of developing breast cancer after menopause is reduced by early full term pregnancy and multiparity. This phenomenon is thought to be associated with the development and differentiation of the breast during pregnancy. METHODS: In order to understand the underlying molecular mechanisms of pregnancy induced breast cancer protection, we profiled and compared the transcriptomes of normal breast tissue biopsies from 71 parous (P) and 42 nulliparous (NP) healthy postmenopausal women using Affymetrix Human Genome U133 Plus 2.0 arrays. To validate the results, we performed real time PCR and immunohistochemistry. RESULTS: We identified 305 differentially expressed probesets (208 distinct genes). Of these, 267 probesets were up- and 38 down-regulated in parous breast samples; bioinformatics analysis using gene ontology enrichment revealed that up-regulated genes in the parous breast represented biological processes involving differentiation and development, anchoring of epithelial cells to the basement membrane, hemidesmosome and cell-substrate junction assembly, mRNA and RNA metabolic processes and RNA splicing machinery. The down-regulated genes represented biological processes that comprised cell proliferation, regulation of IGF-like growth factor receptor signaling, somatic stem cell maintenance, muscle cell differentiation and apoptosis. CONCLUSIONS: This study suggests that the differentiation of the breast imprints a genomic signature that is centered in the mRNA processing reactome. These findings indicate that pregnancy may induce a safeguard mechanism at post-transcriptional level that maintains the fidelity of the transcriptional process

Simulation of dimensionality effects in thermal transport

The discovery of nanostructures and the development of growth and fabrication techniques of one- and two-dimensional materials provide the possibility to probe experimentally heat transport in low-dimensional systems. Nevertheless measuring the thermal conductivity of these systems is extremely challenging and subject to large uncertainties, thus hindering the chance for a direct comparison between experiments and statistical physics models. Atomistic simulations of realistic nanostructures provide the ideal bridge between abstract models and experiments. After briefly introducing the state of the art of heat transport measurement in nanostructures, and numerical techniques to simulate realistic systems at atomistic level, we review the contribution of lattice dynamics and molecular dynamics simulation to understanding nanoscale thermal transport in systems with reduced dimensionality. We focus on the effect of dimensionality in determining the phononic properties of carbon and semiconducting nanostructures, specifically considering the cases of carbon nanotubes, graphene and of silicon nanowires and ultra-thin membranes, underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure

Measurement of the Spin Structure of the Deuteron in the DIS Region

We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4, details adde

Vertebral osteomyelitis caused by Enterococcus faecalis in broiler chickens from southern Brazil

Enterococcal spondylitis affects poultry and causes progressive lameness. This study reports what seems to be the first case of vertebral osteomyelitis caused by Enterococcus in broiler chickens in southern Brazil. We also conducted an experimental infection to evaluate microorganismal characteristics and pathogenicity in broiler chickens. We performed bacterial isolation, identification, and histopathology. The isolates were tested for their growth and survival capacity at different temperatures, pH values, and antimicrobial resistance profiles. The experiment infection was conducted with broiler breeders (n=9). Group 1 = negative control, Group 2 = challenged orally, Group 3 = challenged via air sac. The autopsy was performed on the 50th day of life (DOL). The report showed spondylitis and fusion of thoracic vertebra, accompanied by spinal cord compression, and femoral head necrosis. We used the isolates (n=17) to test their growth at 10°C and 45°C, survival capacity for up to 60° for 30 min, and growth under pH levels from four to 12. Higher resistance was observed against macrolides and quinolones. On experimental infections, all animals expressed signs of lameness and "sitting on the hocks". Enterococcus faecalis is the causal agent of enterococcal spondylitis in broilers in southern Brazil, which is an underreported and emerging pathological condition that requires attention

Magnetocaloric effect in spin-1/2 XXXX chains with three-spin interactions

We consider the exactly solvable spin-1/2 $XX$ chain with the three-spin interactions of the $XZX+YZY$ and $XZY-YZX$ types in an external (transverse) magnetic field. We calculate the entropy and examine the magnetocaloric effect for the quantum spin system. We discuss a relation between the cooling/heating efficiency and the ground-state phase diagram of the quantum spin model. We also compare ability to cool/heat in the vicinity of the quantum critical and triple points. Moreover, we examine the magnetocaloric effect for the spin-1/2 $XX$ chain with three-spin interactions in a random (Lorentzian) transverse magnetic field.Comment: 10 pages, 8 figure