Breakdown of Hydrodynamics in a Simple One-Dimensional Fluid

We investigate the behavior of a one-dimensional diatomic fluid under a shock wave excitation. We find that the properties of the resulting shock wave are in striking contrast with those predicted by hydrodynamic and kinetic approaches, e.g., the hydrodynamic profiles relax algebraically toward their equilibrium values. Deviations from local thermodynamic equilibrium are persistent, decaying as a power law of the distance to the shock layer. Non-equipartition is observed infinitely far from the shock wave, and the velocity-distribution moments exhibit multiscaling. These results question the validity of simple hydrodynamic theories to understand collective behavior in 1d fluids.Comment: 4 pages, 5 figure

Fluctuations of the heat flux of a one-dimensional hard particle gas

Momentum-conserving one-dimensional models are known to exhibit anomalous Fourier's law, with a thermal conductivity varying as a power law of the system size. Here we measure, by numerical simulations, several cumulants of the heat flux of a one-dimensional hard particle gas. We find that the cumulants, like the conductivity, vary as power laws of the system size. Our results also indicate that cumulants higher than the second follow different power laws when one compares the ring geometry at equilibrium and the linear case in contact with two heat baths (at equal or unequal temperatures). keywords: current fluctuations, anomalous Fourier law, hard particle gasComment: 5 figure

EasyLabels: weak labels for scene segmentation in laparoscopic videos

PURPOSE: We present a different approach for annotating laparoscopic images for segmentation in a weak fashion and experimentally prove that its accuracy when trained with partial cross-entropy is close to that obtained with fully supervised approaches. METHODS: We propose an approach that relies on weak annotations provided as stripes over the different objects in the image and partial cross-entropy as the loss function of a fully convolutional neural network to obtain a dense pixel-level prediction map. RESULTS: We validate our method on three different datasets, providing qualitative results for all of them and quantitative results for two of them. The experiments show that our approach is able to obtain at least [Formula: see text] of the accuracy obtained with fully supervised methods for all the tested datasets, while requiring [Formula: see text][Formula: see text] less time to create the annotations compared to full supervision. CONCLUSIONS: With this work, we demonstrate that laparoscopic data can be segmented using very few annotated data while maintaining levels of accuracy comparable to those obtained with full supervision

Colored Non-Crossing Euclidean Steiner Forest

Given a set of $k$-colored points in the plane, we consider the problem of finding $k$ trees such that each tree connects all points of one color class, no two trees cross, and the total edge length of the trees is minimized. For $k=1$, this is the well-known Euclidean Steiner tree problem. For general $k$, a $k\rho$-approximation algorithm is known, where $\rho \le 1.21$ is the Steiner ratio. We present a PTAS for $k=2$, a $(5/3+\varepsilon)$-approximation algorithm for $k=3$, and two approximation algorithms for general~$k$, with ratios $O(\sqrt n \log k)$ and $k+\varepsilon$

Network synchronization: Optimal and Pessimal Scale-Free Topologies

By employing a recently introduced optimization algorithm we explicitely design optimally synchronizable (unweighted) networks for any given scale-free degree distribution. We explore how the optimization process affects degree-degree correlations and observe a generic tendency towards disassortativity. Still, we show that there is not a one-to-one correspondence between synchronizability and disassortativity. On the other hand, we study the nature of optimally un-synchronizable networks, that is, networks whose topology minimizes the range of stability of the synchronous state. The resulting ``pessimal networks'' turn out to have a highly assortative string-like structure. We also derive a rigorous lower bound for the Laplacian eigenvalue ratio controlling synchronizability, which helps understanding the impact of degree correlations on network synchronizability.Comment: 11 pages, 4 figs, submitted to J. Phys. A (proceedings of Complex Networks 2007

Predictive models for the phase behaviour and solution properties of weak electrolytes: nitric, sulfuric and carbonic acid

The distribution of ionic species in electrolyte systems is important in many fields of science and engineering, ranging from the study of degradation mechanisms to the design of systems for electrochemical energy storage. Often, other phenomena closely related to the ionic speciation, such as ion pairing, clustering and hydrogen bonding, which are difficult to investigate experimentally, are also of interest. Here, we develop an accurate molecular approach, accounting for reactions as well as association and ion pairing, to deliver a predictive framework that helps validate experiment and guides future modelling of speciation phenomena of weak electrolytes. We extend the SAFT-VRE Mie equation of state [D. K. Eriksen et al., Mol. Phys., 2016, 114, 2724–2749] to study aqueous solutions of nitric, sulphuric and carbonic acid, considering complete and partially dissociated models. In order to incorporate the dissociation equilibria, correlations to experimental data for the relevant thermodynamic equilibrium constants of the dissociation reactions are taken from the literature and are imposed as a boundary condition in the calculations. The models for water, the hydronium ion, and carbon dioxide are treated as transferable and are taken from our previous work. Here we present new molecular models for nitric acid, and the nitrate, bisulfate, sulfate, and bicarbonate anions. The resulting framework is used to predict a range of phase behaviour and solution properties of the aqueous acids over wide ranges of concentration and temperature, including the degree of dissociation, as well as the activity coefficients of the ionic species, and the activity of water and osmotic coefficient, density, and vapour pressure of the solutions. The SAFT-VRE Mie models obtained in this manner provide a means of elucidating the mechanisms of association and ion pairing in the systems studied, complementing the experimental observations reported in the literature

Áreas homogêneas e teor de água disponível de um Latossolo Vermelho Amarelo.

O entendimento da variabilidade do solo e a amostragem sistemática do horizonte diagnóstico podem ser úteis na definição de estratégias de manejo. Neste contexto, uma abordagem multivariada dos atributos do horizonte diagnóstico do solo pode ser mais eficiente do que a simples caracterização da variabilidade espacial na superfície. O objetivo deste trabalho foi determinar áreas homogêneas do talhão com base na caracterização do horizonte diagnóstico, utilizando técnicas de análise multivariada, promovendo uma abordagem quantitativa do teor de água disponível. Em uma área de Latossolo Vermelho Amarelo, foram coletadas 97 amostras da camada 0,80-1,00 m, dispostas em malha regular de 175 m. Com base na metodologia proposta, foi possível determinar três áreas homogêneas. Uma destas, caracterizada pelos maiores teores de argila, caulinita e carbono orgânico e menor densidade do solo, apresentou maior umidade gravimétrica em equilíbrio com todos os potenciais estudados; porém, essa maior umidade não resultou em maiores teores de água disponível, que foram menores que 0,15 m3.m?3. As outras duas áreas, caracterizadas pelo maior teor de areia fina, apresentaram teores de água disponível maiores que 0,15 m3.m?3, considerado como satisfatório para o adequado desenvolvimento das plantas

Variabilidade e correlação espacial entre atributos e a umidade gravimétrica de um Latossolo Vermelho Amarelo.

O conhecimento das relações entre os atributos da paisagem, físico-hídricos e carbono orgânico de Latossolos deve ser aprimorado. Os objetivos deste trabalho foram: i) avaliar a variabilidade espacial dos atributos físicos da paisagem, do carbono orgânico e da umidade; e, ii) verificar a ocorrência de correlação espacial entre estes atributos e a umidade gravimétrica. Em uma área de Latossolo Vermelho Amarelo, foram coletadas 97 amostras da camada 0,80- 1,00 m, dispostas em malha regular de 175 m. Foram determinados oito atributos do solo, dois da paisagem e a umidade gravimétrica θ?0,001 MPa, θ?0,003 MPa, θ?0,006 MPa, θ?0,100 MPa, θ?1,000 MPa e θ?1,500 MPa. A variabilidade espacial foi analisada por meio de ajustes dos semivariogramas simples, e as correlações espaciais pelos semivariogramas cruzados. O teor de argila, areia fina e declividade apresentou correlação espacial e foi o atributo chave no arranjo espacial da umidade abaixo de θ?0,100 Mpa. O carbono orgânico também apresentou correlação espacial e foi o atributo chave para umidades acima dessa umidade. A variabilidade espacial dos teores de argila, densidade do solo e carbono orgânico, associada à declividade do terreno, pode ser eficaz na determinação de áreas homogêneas e auxiliar no manejo da água em sistemas agrícolas

Desenvolvimento de um algoritmo baseado em sensores ativos de dossel para recomendação da adubação nitrogenada em taxas variáveis.

O uso de sensores ativos de dossel (ACS) para o ajuste da aplicação localizada em tempo real de fertilizantes nitrogenados é promissor na região do Cerrado, onde grande quantidade de fertilizantes à base de nitrogênio (N) são aplicados em doses uniformes. A vantagem desta técnica comparada com a aplicação tradicional em dose uniforme é principalmente na sincronia da aplicação do N com a época ideal de absorção do nutriente pela planta no decurso da cultura considerando a variabilidade espacial. O objetivo deste estudo foi a geração de um primeiro algoritmo para cálculo da dose de N em milho baseado em leituras destes ACS na região do Cerrado. O experimento foi conduzido em fazenda em 7 locais (durante as safras 2010 e 2011), utilizando faixas longas experimentais com diferentes doses de N (0, 72, 144, 216, 288 and 360 kg N ha-1) com três repetições. Cada uma consistiu de uma faixa de 500m de comprimento em sistema de plantio direto em sequeiro. As medições com os sensores foram realizadas entre os estádios fenológicos de V11 e V13 utilizando um sensor ativo de três bandas (infravermelho próximo, vermelho e vermelho próximo) e um clorofilômetro portátil. A produtividade de grãos foi medida com colhedoras equipadas com monitores de produtividade e DGPS. Foi possível a geração de um primeiro algoritmo para utilização no segundo estágio do projeto, onde serão realizadas as validações comparando com outros procedimentos e abordagens para manejo localizado de N

Role of 4-1BB Ligand in Costimulation of T Lymphocyte Growth and its Upregulation on M12 B Lymphomas by cAMP

K46J B lymphomas express a T cell costimulatory activity that is not inhibited by CTLA-4Ig, anti-B7-1, anti-B7-2, anti-intercellular adhesion molecule 1 or antibodies to heat stable antigen. In this paper we report that this costimulatory activity is mediated at least in part by 4-1BB ligand, a member of the tumor necrosis factor (TNF) gene family that binds to 4-1BB, a T cell activation antigen with homology to the TNF/nerve growth factor receptor family. A fusion protein between 4-1BB and alkaline phosphatase (4-1BB-AP) blocks T cell activation by K46J lymphomas in both an antigen-specific system and with polyclonally (anti-CD3) activated T cells. 4-1BB-AP also blocks antigen presentation by normal spleen cells. When the antigen-presenting cells express B7 molecules as well as 4-1BB ligand, we find that B7 molecules and 4-1BB-AP both contribute to T cell activation. These data suggest that 4-1BB ligand plays an important role in costimulation of IL-2 production and proliferation by T cells. The B lymphoma M12 expresses low levels of 4-1BB-L but can be induced to express higher levels by treatment of the B ceils with cAMP, which also induces B7-1 and B7-2 in these cells. Thus cAMP appears to coordinately induce several costimulatory molecules on B cells