The phase diagram of L\'evy spin glasses

We study the L\'evy spin-glass model with the replica and the cavity method. In this model each spin interacts through a finite number of strong bonds and an infinite number of weak bonds. This hybrid behaviour of L\'evy spin glasses becomes transparent in our solution: the local field contains a part propagating along a backbone of strong bonds and a Gaussian noise term due to weak bonds. Our method allows to determine the complete replica symmetric phase diagram, the replica symmetry breaking line and the entropy. The results are compared with simulations and previous calculations using a Gaussian ansatz for the distribution of fields.Comment: 20 pages, 7 figure

Pairing in low-density Fermi gases

We consider pairing in a dilute system of Fermions with a short-range interaction. While the theory is ill-defined for a contact interaction, the BCS equations can be solved in the leading order of low-energy effective field theory. The integrals are evaluated with the dimensional regularization technique, giving analytic formulas relating the pairing gap, the density, and the energy density to the two-particle scattering length.Comment: 12 pages, 2 EPS-figures, uses psfig.sty, eq.(9) correcte

Towards an effective potential for the monomer, dimer, hexamer, solid and liquid forms of hydrogen fluoride

We present an attempt to build up a new two-body effective potential for hydrogen fluoride, fitted to theoretical and experimental data relevant not only to the gas and liquid phases, but also to the crystal. The model is simple enough to be used in Molecular Dynamics and Monte Carlo simulations. The potential consists of: a) an intra-molecular contribution, allowing for variations of the molecular length, plus b) an inter-molecular part, with three charged sites on each monomer and a Buckingham "exp-6" interaction between fluorines. The model is able to reproduce a significant number of observables on the monomer, dimer, hexamer, solid and liquid forms of HF. The shortcomings of the model are pointed out and possible improvements are finally discussed.Comment: LaTeX, 24 pages, 2 figures. For related papers see also http://www.chim.unifi.it:8080/~valle

The Three-Boson System at Next-To-Next-To-Leading Order

We discuss effective field theory treatments of the problem of three particles interacting via short-range forces (range R >> a_2, with a_2 the two-body scattering length). We show that forming a once-subtracted scattering equation yields a scattering amplitude whose low-momentum part is renormalization-group invariant up to corrections of O(R^3/a_2^3). Since corrections of O(R/a_2) and O(R^2/a_2^2) can be straightforwardly included in the integral equation's kernel, a unique solution for 1+2 scattering phase shifts and three-body bound-state energies can be obtained up to this accuracy. We use our equation to calculate the correlation between the binding energies of Helium-4 trimers and the atom-dimer scattering length. Our results are in excellent agreement with the recent three-dimensional Faddeev calculations of Roudnev and collaborators that used phenomenological inter-atomic potentials.Comment: 20 pages, 3 eps figure

Very high rotational frequencies and band termination in 73Br

Rotational bands in 73Br have been investigated up to spins of 65/2 using the EUROBALL III spectrometer. One of the negative-parity bands displays the highest rotational frequency 1.85 MeV reported to date in nuclei with mass number greater than 25. At high frequencies, the experimental dynamic moment of inertia for all bands decrease to very low values, indicating a loss of collectivity. The bands are described in the configuration-dependent cranked Nilsson-Strutinsky model. The calculations indicate that one of the negative-parity bands is observed up to its terminating single-particle state at spin 63/2. This result establishes the first band termination case in the A = 70 mass region.Comment: 6 pages, 6 figures, submitted to Phys. Rev. C as a Rapid Communicatio

Wolbachia and DNA barcoding insects: patterns, potential and problems

Wolbachia is a genus of bacterial endosymbionts that impacts the breeding systems of their hosts. Wolbachia can confuse the patterns of mitochondrial variation, including DNA barcodes, because it influences the pathways through which mitochondria are inherited. We examined the extent to which these endosymbionts are detected in routine DNA barcoding, assessed their impact upon the insect sequence divergence and identification accuracy, and considered the variation present in Wolbachia COI. Using both standard PCR assays (Wolbachia surface coding protein – wsp), and bacterial COI fragments we found evidence of Wolbachia in insect total genomic extracts created for DNA barcoding library construction. When >2 million insect COI trace files were examined on the Barcode of Life Datasystem (BOLD) Wolbachia COI was present in 0.16% of the cases. It is possible to generate Wolbachia COI using standard insect primers; however, that amplicon was never confused with the COI of the host. Wolbachia alleles recovered were predominantly Supergroup A and were broadly distributed geographically and phylogenetically. We conclude that the presence of the Wolbachia DNA in total genomic extracts made from insects is unlikely to compromise the accuracy of the DNA barcode library; in fact, the ability to query this DNA library (the database and the extracts) for endosymbionts is one of the ancillary benefits of such a large scale endeavor – for which we provide several examples. It is our conclusion that regular assays for Wolbachia presence and type can, and should, be adopted by large scale insect barcoding initiatives. While COI is one of the five multi-locus sequence typing (MLST) genes used for categorizing Wolbachia, there is limited overlap with the eukaryotic DNA barcode region

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand

Evolution of defence portfolios in exploiter-victim systems

Some organisms maintain a battery of defensive strategies against their exploiters (predators, parasites or parasitoids), while others fail to employ a defence that seems obvious. In this paper, we shall investigate the circumstances under which defence strategies might be expected to evolve. Brood parasites and their hosts provide our main motivation, and we shall discuss why the reed warbler Acrocephalus scirpaceus has evolved an egg-rejection but not a chick-rejection strategy as a defence against the common (Eurasian) cuckoo Cuculus canorus, while the superb fairy-wren Malurus cyaneus has evolved a chick-rejection but not an egg-rejection strategy as a defence against Horsfield's bronze-cuckoo Chrysococcyx basalis. We suggest that the answers lie in strategy-blocking, where one strategy (the blocking strategy) prevents the appearance of another (the blocked strategy) that would be adaptive in its absence. This may be common in exploiter-victim systems. © 2006 Springer Science+Business Media, Inc

Evaluation of the process of reabilitation of a stretch of Riparian forest in Itapemirim river watershed - ES

Este estudo foi realizado em uma área de floresta ciliar em processo de recuperação mediante reabilitação.A área de estudo está localizada na sub-bacia hidrográfica do rio Itapemirim, no Município de Alegre, ES, Brasil.A ocupação e uso do solo antes da revegetação eram de pastagem com Brachiaria sp. A revegetação da áreafoi feita em 1997, com espécies autóctones e alóctones arbóreas, em arranjo de distribuição aleatório, em umaárea de 1,2 ha. Para a realização dos estudos foram feitos inventários florestais nos períodos de 2004/2005e 2005/2006, sendo medidos os indivíduos de hábito arbustivo e arbóreo com circunferência à altura do peito(CAP) > 5 cm e suas alturas totais. As espécies encontradas na área foram identificadas e classificadas de acordocom seus grupos ecológicos, síndromes de dispersão e presença silvestre, sendo calculados os parâmetros florísticos,a estrutura vertical e a dinâmica estrutural desse povoamento. O objetivo do trabalho foi avaliar o desenvolvimentodo povoamento implantado para subsidiar práticas silviculturais quanto à seleção e implantação de espécies pararevegetação de áreas de floresta ciliar degradadas, em condições semelhantes. Os resultados demonstraram quefoi implantado um povoamento florestal com grande diversidade de espécies e a estratificação em classes dealtura foi à semelhança de povoamentos heterogêneos naturais. As espécies identificadas como edificadoras darevegetação da área estudada foram: Anadenanthera colubrina, Caesalpinia leyostachia, Acacia auriculiformis,Acacia mangium, Handroanthus serratifolius, Inga edulis, Joannesia princeps, Pterogyne nitens, Enterelobiumcontortisiliquum, Tabernaemontana hystrix e Anthocephalus indicus. A distribuição em classes de tamanho dacomunidade implantada ocorre em forma de "J" reverso, havendo a predominância de indivíduos pioneiros emtodas as classes de CAP. A dinâmica da estrutura horizontal apontou que, para o sucesso, continuidade e desenvolvimentoda recuperação da área, seja monitorada a regeneração natural em relação à sua presença e à eficiência dos fatoresbióticos e abióticos que nela interferem. A não observância de indivíduos arbustivos e arbóreos regenerados naturalmente,na classe de inclusão do estudo, indica a fragilidade inicial da área rumo à sustentabilidade do sistema.The study was realized in an area of riparian forest in process by means of rehabilitation. Thestudy area is located in Rio Itapemirim, in Alegre city, Brazil. The occupation and use of the soil beforethe recovery were of pasture with Brachiaria sp. The recovery of this area was in 1997, with autochthonousand allochthonous species, in casually distribution arrangement, in an area of 1,2 ha. For this studies wasrealized forest inventories in the periods of 2004/2005 and 2005/2006, being measured the arboreal individualswith circumference at breast height (CBH) and total heights. The species found in the area were identifiedand classified in this ecological groups, dispersion syndromes and wild presence, it forms calculated thefloristic parameters, the vertical structure and the structural dynamics of this plantation. The objective ofthis work went evaluate the development of the plantation implanted to subsidize practical silviculture withrelationship to the selection and plantation of species for the revegetation of degraded areas of riparianforest, in similar conditions. The results of the studies demonstrated that a forest plantation was implantedwith great diversity of species and the bedding in height classes it went to the likeness of natural heterogeneous.The species identified as builders of the plantation of the studied area were: Anadenanthera colubrina, Caesalpinia leyostachia, Acacia auriculiformis, Acacia mangium, Handroanthus serratifolius, Inga edulis, Joannesia princeps,Pterogyne nitens, Enterelobium contortisiliquum, Tabernaemontana hystrix, and Anthocephalus indicus . Theimplanted community's distribution diametric happens in reverse J shape having the pioneer individuals'predominance in all the classes of CBH. The dynamics of the horizontal structure points that for the success,continuity and development of the recovery of the area, the natural regeneration be monitored in relationto its presence and efficiency of the biotic factors and abiotic those interfere in the same. The not tree individualsobservance in natural regeneration, in the class of inclusion of the study, indicate the initial fragility of thearea heading for sustentabilidade of the system