IPCC global coupled model simulations of the South America monsoon system

This study examines the variability of the South America monsoon system (SAMS) over tropical South America (SA). The onset, end, and total rainfall during the summer monsoon are investigated using precipitation pentad estimates from the global precipitation climatology project (GPCP) 1979-2006. Likewise, the variability of SAMS characteristics is examined in ten Intergovernmental Panel on Climate Change (IPCC) global coupled climate models in the twentieth century (1981-2000) and in a future scenario of global change (A1B) (2081-2100). It is shown that most IPCC models misrepresent the intertropical convergence zone and therefore do not capture the actual annual cycle of precipitation over the Amazon and northwest SA. Most models can correctly represent the spatiotemporal variability of the annual cycle of precipitation in central and eastern Brazil such as the correct phase of dry and wet seasons, onset dates, duration of rainy season and total accumulated precipitation during the summer monsoon for the twentieth century runs. Nevertheless, poor representation of the total monsoonal precipitation over the Amazon and northeast Brazil is observed in a large majority of the models. Overall, MI-ROC3.2-hires, MIROC3.2-medres and MRI-CGCM3.2.3 show the most realistic representation of SAMS`s characteristics such as onset, duration, total monsoonal precipitation, and its interannual variability. On the other hand, ECHAM5, GFDL-CM2.0 and GFDL-CM2.1 have the least realistic representation of the same characteristics. For the A1B scenario the most coherent feature observed in the IPCC models is a reduction in precipitation over central-eastern Brazil during the summer monsoon, comparatively with the present climate. The IPCC models do not indicate statistically significant changes in SAMS onset and demise dates for the same scenario.

An analysis of the environmental energetics associated with the transition of the first South Atlantic hurricane

This study presents the first analysis of the energetics associated with a hybrid cyclone`s transition in the Southern Hemisphere, Hurricane Catarina ( March 2004). Catarina has earned a place in history as the first documented South Atlantic hurricane, but its unusual tropical transition is still poorly understood. Here we show that Catarina`s transition was preceded by marked environmental changes in the Lorenz energy cycle, with an abrupt shift from a baroclinic to a predominantly barotropic state. Such changes help to explain the unusual vortex`s growth until its transition was completed. Although the vortex`s energy flux is not explicitly calculated, a likely mechanism linking the environmental energetics with Catarina is the extraction of eddy kinetic energy from horizontal momentum and heat transfers within the through component of the blocking. The results advance the understanding of this rare event and suggest that the technique has a great potential to study transitioning systems in general.

On the generic identity of Odontophrynus moratoi Jim & Caramaschi, 1980 (Anura, Cycloramphidae)

The generic identity of Odontophrynus moratoi is controversial since the original description due to the presence of intermediate morphological features between the genera Odontophrynus and Proceratophrys. Herein we performed molecular analyses of three genes (16S, cyt b and Rag-1) and recovered O. moratoi deeply imbedded inside a clade containing only Proceratophrys species, appearing as the sister group of Proceratophrys concavitympanum. Therefore, this study formally transfers the species O. moratoi to the genus Proceratophrys [Proceratophrys moratoi (Jim & Caramaschi 1980) comb. nov].

Switching control of sympathetic activity from forebrain to hindbrain in chronic dehydration

We investigated the mechanisms responsible for increased blood pressure and sympathetic nerve activity (SNA) caused by 2-3 days dehydration (DH) both in vivo and in situ preparations. In euhydrated (EH) rats, systemic application of the AT(1) receptor antagonist Losartan and subsequent pre-collicular transection (to remove the hypothalamus) significantly reduced thoracic (t) SNA. In contrast, in DH rats, Losartan, followed by pre-collicular and pontine transections, failed to reduce tSNA, whereas transection at the medulla-spinal cord junction massively reduced tSNA. In DH but not EH rats, selective inhibition of the commissural nucleus tractus solitarii (cNTS) significantly reduced tSNA. Comparable data were obtained in both in situ and in vivo (anaesthetized/conscious) rats and suggest that following chronic dehydration, the control of tSNA transfers from supra-brainstem structures (e. g. hypothalamus) to the medulla oblongata, particularly the cNTS. As microarray analysis revealed up-regulation of AP1 transcription factor JunD in the dehydrated cNTS, we tested the hypothesis that AP1 transcription factor activity is responsible for dehydration-induced functional plasticity. When AP1 activity was blocked in the cNTS using a viral vector expressing a dominant negative FosB, cNTS inactivation was ineffective. However, tSNA was decreased after pre-collicular transection, a response similar to that seen in EHrats. Thus, the dehydration-induced switch in control of tSNA from hypothalamus to cNTS seems to be mediated via activation of AP1 transcription factors in the cNTS. If AP1 activity is blocked in the cNTS during dehydration, sympathetic activity control reverts back to forebrain regions. This unique reciprocating neural structure-switching plasticity between brain centres emphasizes the multiple mechanisms available for the adaptive response to dehydration.

Iterative strong coupling of dimensionally heterogeneous models

In this article we address decomposition strategies especially tailored to perform strong coupling of dimensionally heterogeneous models, under the hypothesis that one wants to solve each submodel separately and implement the interaction between subdomains by boundary conditions alone. The novel methodology takes full advantage of the small number of interface unknowns in this kind of problems. Existing algorithms can be viewed as variants of the `natural` staggered algorithm in which each domain transfers function values to the other, and receives fluxes (or forces), and vice versa. This natural algorithm is known as Dirichlet-to-Neumann in the Domain Decomposition literature. Essentially, we propose a framework in which this algorithm is equivalent to applying Gauss-Seidel iterations to a suitably defined (linear or nonlinear) system of equations. It is then immediate to switch to other iterative solvers such as GMRES or other Krylov-based method. which we assess through numerical experiments showing the significant gain that can be achieved. indeed. the benefit is that an extremely flexible, automatic coupling strategy can be developed, which in addition leads to iterative procedures that are parameter-free and rapidly converging. Further, in linear problems they have the finite termination property. Copyright (C) 2009 John Wiley & Sons, Ltd.

GRASP heuristic with path-relinking for the multi-plant capacitated lot sizing problem

This paper addresses the independent multi-plant, multi-period, and multi-item capacitated lot sizing problem where transfers between the plants are allowed. This is an NP-hard combinatorial optimization problem and few solution methods have been proposed to solve it. We develop a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic as well as a path-relinking intensification procedure to find cost-effective solutions for this problem. In addition, the proposed heuristics is used to solve some instances of the capacitated lot sizing problem with parallel machines. The results of the computational tests show that the proposed heuristics outperform other heuristics previously described in the literature. The results are confirmed by statistical tests. (C) 2009 Elsevier B.V. All rights reserved.

Reaction functions for weakly bound systems

We propose a new technique to analyze total reaction cross sections. In this technique, which has been previously applied to fusion reactions, the experimental data are used to build a dimensionless reaction function, which does not depend oil the system size or details of the optical potential. In this way, total reaction cross sections for different systems can be directly compared. We employ this technique to perform a systematic study of reaction cross sections of weakly bound systems in different mass ranges, and compare their reaction functions with the ones of tightly bound systems with similar masses. We show that breakup reactions and neutron transfers in halo systems lead to large reaction functions, well above the ones of typical tightly or weakly bound stable systems. (C) 2009 Elsevier B.V. All rights reserved.

Energy transfer processes in Yb(3+)-Tm(3+) co-doped sodium alumino-phosphate glasses with improved 1.8 mu m emission

Sodium alumino-phosphate glasses co-doped with Yb(3+) and Tm(3+) ions have been prepared with notably low OH(-) content, and characterized from the viewpoint of their spectroscopic properties. In these glasses, Yb(3+) acts as an efficient sensitizer of excitation energy at 0.98 mu m - which can be provided by high power and low cost diode lasers, and subsequently undergoes non-resonant energy transfer to Tm(3+) ions ((2)F(5/2), (3)H(6) --> (2)F(7/2), (3)H(5)). Through this process, the emitting level (3)F(4) is rapidly populated, generating improved emission at 1.8 mu m ((3)F(4) --> (3)H(6)). In order to guarantee the efficiency of such favorable energy transfer, energy losses via multiphonon decay, Yb-Yb radiative trapping, and non- radiative transfer to OH(-) groups were evaluated, and minimized when possible. The dipole - dipole energy transfer microscopic parameters corresponding to Yb(3+) --> Tm(3+), Yb(3+) --> Yb(3+) and Tm(3+) --> Tm(3+) transfers, calculated by the Forster-Dexter model, are C(Yb-Tm) = 2.9 x 10(-40) cm(6) s(-1), C(Yb-Yb) = 42 x 10(-40) cm(6) s(-1) and C(Tm-Tm) = 43 x 10(-40) cm(6) s(-1), respectively.

L-(2-Quinolyl)-2-naphthol: A new intra-intermolecular photoacid-photobase molecule

Photochemical and photophysical properties of 1-(2-quinolyl)-2-naphthol (2QN) in water and organic solvents, as well in glassy media were studied to investigate the occurrence of intramolecular excited state prototropic reactions between the naphthol and quinoline rings. Spectral data show the two chromophores apparently behaving independently. However, in acid aqueous media or in low polarity solvents a new electronic transition red shifted band with respect to that of the parent compounds assigned to an intramolecular H-bond and to a quinoid form, respectively, shows up. Model calculations and R-X data lend support to a minimum energy conformer having a dihedral angle of similar to 39 degrees between the two groups. Singlet excited state properties (S-1) show a high suppressive effect of one ring over the other, resulting in very low emission yields at room temperature. The occurrence of excited state intramolecular proton transfer is observed in water (zwitter ion form) and in low polarity media (quinoid form) and originates from a previously CT H-bonded state. Phosphorescence data allowed a reasonable description of the electronic states of 2QN. In addition two new derivatives were prepared having the N atom blocked by methylation and both the N and O groups blocked by a CH2 bridge. The spectral data of these two compounds confirmed the attributions made for 2QN. (C) 2007 Elsevier B.V. All rights reserved.

The electrochemical effect of acid functionalisation of carbon nanotubes to be used in sensors development

The electrochemical behaviour of multi-walled carbon nanotubes was compared with that of glassy carbon, and the differences were investigated by cyclic voltammetry and electrochemical impedance spectroscopy before and after acid pre-treatment. The electrochemical techniques showed that acid functionalisation significantly improves the electrocatalytic properties of carbon nanotubes. These electrocatalytic properties enhance the analytical signal, shift the oxidation peak potential to a less positive value, and the charge-transfers rate increase of both dopamine and K(4)[Fe(CN)(6)]. The functionalisation step and the resulting appearance of edge planes covered with different chemical groups were confirmed by FTIR measurements. Carbon nanotubes after acid pre-treatment are a potentially powerful analytical tool for sensor development. (C) 2010 Elsevier B.V. All rights reserved.