557 research outputs found

    Corecursive featherweight Java revisited

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    We describe a Java-like calculus which supports cyclic data structures, and offers a mechanism of flexible regular corecursion for their manipulation. The calculus enhances an earlier proposal by a more sophisticated reduction semantics, which filters out, by an additional check, some spurious results which were obtained in the previous model

    Vortex nucleation in mesoscopic Bose superfluid and breaking of the parity symmetry

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    We analyze vortex nucleation in mezoscopic 2D Bose superfluid in a rotating trap. We explicitly include a weakly anisotropic stirring potential, breaking thus explicitly the axial symmetry. As the rotation frequency passes the critical value Ωc\Omega_c the system undergoes an extra symmetry change/breaking. Well below Ωc\Omega_c the ground state is properly described by the mean field theory with an even condensate wave function. Well above Ωc\Omega_c the MF solution works also well, but the order parameter becomes odd. This phenomenon involves therefore a discrete parity symmetry breaking. In the critical region the MF solutions exhibit dynamical instability. The true many body state is a strongly correlated entangled state involving two macroscopically occupied modes (eigenstates of the single particle density operator). We characterize this state in various aspects: i) the eligibility for adiabatic evolution; ii) its analytical approximation given by the maximally entangled combination of two single modes; and finally iii) its appearance in particle detection measurements.Comment: 14 pages, 27 figure

    Reproductive traits of the invasive species Acacia dealbata Link. in the northern Mediterranean basin

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    Among the many exotic plants introduced in the last two centuries in Northern Mediterranean Basin Acacia dealbata Link. is one of the most invasive. Despite its presence in the region since many years, it has not yet been investigated how the species has established itself and has formed small forests. In this study, we aimed to gather data on reproductive trait of the invasive species A. dealbata at the northern limit of the Mediterranean bioclimatic region. In six naturalized populations, fruit and seed set were estimated and seed germination was tested in laboratory. Two out of the six populations failed to set fruits, and the fruit set was always low as observed in other invaded areas of the world. Only three populations produced germinating seeds whose rates were comparable to other invasive areas. The seeds may constitute a long-lasting seed bank that may favour the colonization of the species in areas disturbed by external factors. In conclusion, the reproductive system may contributes only partially to the spread and invasiveness of the species in the Northern Mediterranean basin, while the plant to spread itself adopts also other vegetative strategies

    Ordered structures in rotating ultracold Bose gases

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    The characterization of small samples of cold bosonic atoms in rotating microtraps has recently attracted increasing interest due to the possibility to deal with a few number of particles per site in optical lattices. We analyze the evolution of ground state structures as the rotational frequency Ω\Omega increases. Various kinds of ordered structures are observed. For N<10N<10 atoms, the standard scenario, valid for large sytems, is absent, and only gradually recovered as NN increases. The vortex contribution to the total angular momentum LL as a function of Ω\Omega ceases to be an increasing function of Ω\Omega, as observed in experiments of Chevy {\it et al.} (Phys. Rev. Lett. 85, 2223 (2000)). Instead, for small NN, it exhibits a sequence of peaks showing wide minima at the values of Ω\Omega, where no vortices appear.Comment: 35 pages, 17 figure

    Tecnologia social: uma estratégia para o desenvolvimento

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    Esta publicação apresenta reflexões de diversos representantes de instituições governamentais, do terceiro setor, da sociedade civil e de universidades sobre o tema da Tecnologia Social

    Tecnologias sociais: as organizações não governamentais no enfrentamento das mudanças climáticas e na promoção de desenvolvimento humano

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    De acordo com o quarto relatório do Intergovernmental Panel on Climate Change (IPCC), as regiões semiáridas do mundo estarão entre as mais afetadas pelos impactos das mudanças climáticas globais. Estudos realizados pelo Ministério do Meio Ambiente (MMA), em 2007, confirmam que, no Nordeste brasileiro, não apenas choverá menos e mais irregularmente, mas, também, haverá mais secas, devido ao aquecimento da temperatura. Diante dos diversos impactos sociais, ambientais e econômicos possíveis nesses cenários, é de fundamental importância a verificação de alternativas sustentáveis para o semiárido brasileiro. Este artigo tem por objetivo avaliar o potencial de algumas das tecnologias sociais (TS) de convivência com o semiárido, desenvolvidas por diversas organizações, para a mitigação das mudanças climáticas e a promoção de desenvolvimento humano. Constata-se que as TS tem grande potencial para auxiliar na mitigação e na adaptação das mudanças climáticas, ao mesmo tempo que promovem melhorias na qualidade de vida das localidades onde estão sendo desenvolvidas

    Obtención de bietanol a partir de la celulosa presente en cascarilla de arroz y aserrín de algarrobo

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    El bioetanol producido a partir de residuos agro industriales es una alternativa muy interesante para diversificar la matriz energética Argentina. La cascarilla de arroz y el aserrín de algarrobo son residuos muy abundantes en la región del NEA y podrían ser aprovechados, utilizándolos como materia prima para la producción de bioetanol combustible. Por ello, el objetivo de este trabajo fue la obtención de bioetanol a partir de estos residuos lignocelulósicos a través de un proceso de pretratamiento ácido, seguido de hidrólisis enzimática y fermentación, evaluando la conveniencia de la primera etapa. El sólido pretratado de cascarilla de arroz presentó un 52,8% de glucanos, de los cuales se convirtieron el 55,7%, luego de la hidrólisis enzimática a las 72h y solo un 19,7% en cascarilla sin tratar. Para el caso del aserrín de algarrobo se encontró, luego del pretratamiento, un sólido con 51,2% de glucanos y a las 72h de hidrólisis enzimática se alcanzó un 41,5% de conversión en el material pretratado y solo un 9,6%, en el material original. Los rendimientos de la fermentación de los hidrolizados fueron aproximadamente del 100% en todos los casos.Bioethanol produced from agro-industrial waste is a very interesting alternative to diversify the energy matrix of Argentina. The rice husk and sawdust carob are abundant residues in the NEA region and could be exploited by using them as raw material for the production of bioethanol fuel. Therefore, the aim of this work was to obtain bioethanol from these lignocellulosic residues through a process of acid pretreatment followed by enzymatic hydrolysis and fermentation, assessing the appropriateness of the first stage. The solid pretreated rice hull presented glucan 52.8%, of which 55.7% are converted, after the enzymatic hydrolysis for 72 hours and only 19.7% in untreated scale. In the case of carob sawdust was found after pretreatment with a solid glucan 51.2% 72h and enzymatic hydrolysis reached 41.5% conversion to the pretreated material, and only 9.6%, in the original material. Fermentation yields of the hydrolysates were approximately 100% in all cases.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    End-to-End Real-time Catheter Segmentation with Optical Flow-Guided Warping during Endovascular Intervention

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    Accurate real-time catheter segmentation is an important pre-requisite for robot-assisted endovascular intervention. Most of the existing learning-based methods for catheter segmentation and tracking are only trained on small-scale datasets or synthetic data due to the difficulties of ground-truth annotation. Furthermore, the temporal continuity in intraoperative imaging sequences is not fully utilised. In this paper, we present FW-Net, an end-to-end and real-time deep learning framework for endovascular intervention. The proposed FW-Net has three modules: a segmentation network with encoder-decoder architecture, a flow network to extract optical flow information, and a novel flow-guided warping function to learn the frame-to-frame temporal continuity. We show that by effectively learning temporal continuity, the network can successfully segment and track the catheters in real-time sequences using only raw ground-truth for training. Detailed validation results confirm that our FW-Net outperforms state-of-the-art techniques while achieving real-time performance.Comment: ICRA 202

    The mammary gland is a sensitive pubertal target in CD-1 and C57Bl/6 mice following perinatal perfluorooctanoic acid (PFOA) exposure

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    Perfluorooctanoic acid (PFOA) is a known developmental toxicant in mice, with varied strain outcomes depending on dose and period of exposure. The impact of PFOA on female mouse pubertal development at low doses (≤1 mg/kg), however, has yet to be determined. Therefore, female offspring from CD-1 and C57Bl/6 dams exposed to PFOA, creating serum concentrations similar to humans, were examined for pubertal onset, including mammary gland development. Mouse pups demonstrated a shorter PFOA elimination half-life than that reported for adult mice. Prenatal exposure to PFOA caused significant mammary developmental delays in exposed female offspring in both strains. Delays started during puberty and persisted into young adulthood; severity was dose-dependent. In contrast, an evaluation of serum hormone levels and pubertal timing onset in the same offspring revealed no effects of PFOA compared to controls in either strain. Therefore, our data suggest that the mammary gland is more sensitive to the effects of early low level PFOA exposures compared to other pubertal endpoints, regardless of strain
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