Defect-induced spin-glass magnetism in incommensurate spin-gap magnets

We study magnetic order induced by non-magnetic impurities in quantum paramagnets with incommensurate host spin correlations. In contrast to the well-studied commensurate case where the defect-induced magnetism is spatially disordered but non-frustrated, the present problem combines strong disorder with frustration and, consequently, leads to spin-glass order. We discuss the crossover from strong randomness in the dilute limit to more conventional glass behavior at larger doping, and numerically characterize the robust short-range order inherent to the spin-glass phase. We relate our findings to magnetic order in both BiCu2PO6 and YBa2Cu3O6.6 induced by Zn substitution.Comment: 6 pages, 5 figs, (v2) real-space RG results added; discussion extended, (v3) final version as publishe

A formação do quadro de pesquisadores da EMBRAPA: estudo de caso.

Descreve o processo pelo qual foi formado o quadro de pesquisadores da EMBRAPA. Apresenta problemas que levaram a decisão de se criar programas de formação de pessoal e as alternativas que se dispunham, a época, para resolver estes problemas

Collaboration networks from a large CV database: dynamics, topology and bonus impact

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions and funding agencies. Here we propose the use of a large and multidisciplinar database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. In this database, detailed information about publications and researchers are made available by themselves so that coauthorship is unambiguous and individuals can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity.We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike. Finally, our analysis reveals that the distinctive collaboration profile of researchers awarded with governmental scholarships suggests a strong bonus impact on their productivity.Comment: 8 pages, 8 figure

Avaliação de híbridos interespecíficos de Elaeis guineensis x Elaeis oleifera.

bitstream/item/57579/1/CPATU-PA121.pd

Sistemas de produção em policultivo de mandioca, milho e caupi para a microrregião Bragantina-Pará.

bitstream/item/33619/1/CPATU-CirTec4.pd

Automated mining of the ALMA archive in the COSMOS field (A3COSMOS): II. Cold molecular gas evolution out to Redshift 6

We present new measurements of the cosmic cold molecular gas evolution out to redshift 6 based on systematic mining of the ALMA public archive in the COSMOS deep field (A3COSMOS). Our A3COSMOS dataset contains ~700 galaxies (0.3 < z < 6) with high-confidence ALMA detections in the (sub-)millimeter continuum and multi-wavelength spectral energy distributions (SEDs). Multiple gas mass calibration methods are compared and biases in band conversions (from observed ALMA wavelength to rest-frame Rayleigh-Jeans(RJ)-tail continuum) have been tested. Combining our A3COSMOS sample with ~1,000 CO-observed galaxies at 0 < z < 4 (75% at z < 0.1), we parameterize galaxies' molecular gas depletion time and molecular gas to stellar mass ratio (gas fraction) each as a function of the stellar mass, offset from the star-forming main sequence (Delta MS) and cosmic age (or redshift). Our proposed functional form provides a statistically better fit to current data (than functional forms in the literature), and implies a "downsizing" effect (i.e., more-massive galaxies evolve earlier than less-massive ones) and "mass-quenching" (gas consumption slows down with cosmic time for massive galaxies but speeds up for low-mass ones). Adopting galaxy stellar mass functions and applying our function for gas mass calculation, we for the first time infer the cosmic cold molecular gas density evolution out to redshift 6 and find agreement with CO blind surveys as well as semi-analytic modeling. These together provide a coherent picture of cold molecular gas, SFR and stellar mass evolution in galaxies across cosmic time

The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems

In this work we examine the Cauchy convergence of both post-Newtonian (T-approximant) and re-summed post-Newtonian (P-approximant) templates for the case of a test-mass orbiting a Kerr black hole along a circular equatorial orbit. The Cauchy criterion demands that the inner product between the $n$ and $n+1$ order approximation approaches unity, as we increase the order of approximation. In previous works, it has been shown that we achieve greater fitting factors and better parameter estimation using the P-approximant templates for both Schwarzschild and Kerr black holes. In this work, we show that the P-approximant templates also display a faster Cauchy convergence making them a superior template to the standard post-Newtonian templates.Comment: 5 pages, Replaced with shortened published versio