Genomic homeology between Pennisetum purpureum and Pennisetum glaucum (Poaceae).

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A New Linear Logic for Deadlock-Free Session-Typed Processes

The π -calculus, viewed as a core concurrent programming language, has been used as the target of much research on type systems for concurrency. In this paper we propose a new type system for deadlock-free session-typed π -calculus processes, by integrating two separate lines of work. The first is the propositions-as-types approach by Caires and Pfenning, which provides a linear logic foundation for session types and guarantees deadlock-freedom by forbidding cyclic process connections. The second is Kobayashi’s approach in which types are annotated with priorities so that the type system can check whether or not processes contain genuine cyclic dependencies between communication operations. We combine these two techniques for the first time, and define a new and more expressive variant of classical linear logic with a proof assignment that gives a session type system with Kobayashi-style priorities. This can be seen in three ways: (i) as a new linear logic in which cyclic structures can be derived and a CYCLE -elimination theorem generalises CUT -elimination; (ii) as a logically-based session type system, which is more expressive than Caires and Pfenning’s; (iii) as a logical foundation for Kobayashi’s system, bringing it into the sphere of the propositions-as-types paradigm

Quantum Conductance in Semimetallic Bismuth Nanocontacts

Electronic transport properties of bismuth nanocontacts are analyzed by means of a low temperature scanning tunneling microscope. The subquantum steps observed in the conductance versus elongation curves give evidence of atomic rearrangements in the contact. The underlying quantum nature of the conductance reveals itself through peaks in the conductance histograms. The shape of the conductance curves at 77 K is well described by a simple gliding mechanism for the contact evolution during elongation. The strikingly different behaviour at 4 K suggests a charge carrier transition from light to heavy ones as the contact cross section becomes sufficiently small.Comment: 5 pages including 4 figures. Accepted for publication in Phys. Rev. Let

Calibration of the length of a chain of single gold atoms

Using a scanning tunneling microscope or mechanically controllable break junctions it has been shown that it is possible to control the formation of a wire made of single gold atoms. In these experiments an interatomic distance between atoms in the chain of ~3.6 Angstrom was reported which is not consistent with recent theoretical calculations. Here, using precise calibration procedures for both techniques, we measure length of the atomic chains. Based on the distance between the peaks observed in the chain length histogram we find the mean value of the inter-atomic distance before chain rupture to be 2.6 +/- 0.2 A . This value agrees with the theoretical calculations for the bond length. The discrepancy with the previous experimental measurements was due to the presence of He gas, that was used to promote the thermal contact, and which affects the value of the work function that is commonly used to calibrate distances in scanning tunnelling microscopy and mechanically controllable break junctions at low temperatures.Comment: 6 pages, 6 figure

Performance of intraspecific hybrids (Kouillou x Robusta) of Coffea canephora Pierre.

The experiment was carried out in 2005 in the municipality of Ouro Preto do Oeste at the experimental station of Embrapa Rondônia. 256 genotypes were evaluated, from nine hybridizations among parents of Kouillou (Cpafro 121, Cpafro 194, Cpafro 199 and Emcapa 03) and Robusta (Robusta 1675, Robusta 2258 and Robusta 640). The experimental design was a randomized complete block design, where each cross was represented by a maximum of 32 plants, distributed in four replications. The spacing used was 3.5 x 1.5 m. The average of six harvests and the yield of hulled coffee was 74.90 bags ha-1. Highlight for progeny is Emcapa 03 x Cpafro 194 with average yield of 97.71 bags ha-1. The estimated heritability observed for yield of coffee benefited, was 78.96%. The evaluation of six production seasons was allowed to verify the reliability of the genetic parameters in each set of crops. It was possible to observe that only the evaluation of the 1st and 2nd crops would be enough to estimate the genetic parameters with efficiency, with a coefficient of determination (R2) of 79.10%. With the inclusion of the 3rd crop, R2 estimates rose to 81.10%. The individual evaluations (per plant) carried out in 2006/2007, 2007/2008 and 2008/2009 crops showed the superiority of the plants from crosses 7, 8 and 9. In relation to resistance of orange rust, most of the genotypes were resistant to disease, and 75% of the genotypes did not present any type of infection symptoms. Among the susceptible genotypes, there was a variation between 1 and 15% in the degree of lesion intensity

Mechanical properties and formation mechanisms of a wire of single gold atoms

A scanning tunneling microscope (STM) supplemented with a force sensor is used to study the mechanical properties of a novel metallic nanostructure: a freely suspended chain of single gold atoms. We find that the bond strength of the nanowire is about twice that of a bulk metallic bond. We perform ab initio calculations of the force at chain fracture and compare quantitatively with experimental measurements. The observed mechanical failure and nanoelastic processes involved during atomic wire fabrication are investigated using molecular dynamics (MD) simulations, and we find that the total effective stiffness of the nanostructure is strongly affected by the detailed local atomic arrangement at the chain bases.Comment: To be published in Phys. Rev. Lett. 4 pages with 3 figure

The use of retorted oil shale as urea coating does not modify chemical parameters of free-drained soil solution.

The objective of this work was to investigate the possible contamination of soil solution with chemical elements present in the composition of retorted oil shale (ROS) when used together with nitrogen fertilization as urea. The experiment was conducted in a silvopastoral system with an experimental design of randomized blocks, with subdivided plots. The main treatments consisted of spatial arrangements of trees, while the split plots constituted the broadcast application of urea (U) and urea covered with ROS (U+ROS). Regardless of the spacing of the trees, the use of U + ROS implied no significant effect on the chemical parameters of the soil solution leached at 40 cm of soil depth. The heavy metals Cd, As, Al and Pb, the most hazardous trace elements present in ROS, were not even detected in soil solution, in none sampling event. Such results are mainly attributed to their low contents in ROS. Our results evidenced that, even with large and cumulative rates of ROS application, the potential for contamination of water table with ROS-derived trace elements is negligible in the soil and climate conditions of the present study. Thus, the use of ROS together with nitrogen fertilization has a potential in the use in agriculture, increasing the efficiency of nitrogen fertilization without causing environmental impacts

The use of retorted oil shale as urea coating does not modify chemical parameters of free-drained soil solution.

The objective of this work was to investigate the possible contamination of soil solution with chemical elements present in the composition of retorted oil shale (ROS) when used together with nitrogen fertilization as urea. The experiment was conducted in a silvopastoral system with an experimental design of randomized blocks, with subdivided plots. The main treatments consisted of spatial arrangements of trees, while the split plots constituted the broadcast application of urea (U) and urea covered with ROS (U+ROS). Regardless of the spacing of the trees, the use of U + ROS implied no significant effect on the chemical parameters of the soil solution leached at 40 cm of soil depth. The heavy metals Cd, As, Al and Pb, the most hazardous trace elements present in ROS, were not even detected in soil solution, in none sampling event. Such results are mainly attributed to their low contents in ROS. Our results evidenced that, even with large and cumulative rates of ROS application, the potential for contamination of water table with ROS-derived trace elements is negligible in the soil and climate conditions of the present study. Thus, the use of ROS together with nitrogen fertilization has a potential in the use in agriculture, increasing the efficiency of nitrogen fertilization without causing environmental impacts