Minimizing the Cost of Team Exploration

A group of mobile agents is given a task to explore an edge-weighted graph $G$, i.e., every vertex of $G$ has to be visited by at least one agent. There is no centralized unit to coordinate their actions, but they can freely communicate with each other. The goal is to construct a deterministic strategy which allows agents to complete their task optimally. In this paper we are interested in a cost-optimal strategy, where the cost is understood as the total distance traversed by agents coupled with the cost of invoking them. Two graph classes are analyzed, rings and trees, in the off-line and on-line setting, i.e., when a structure of a graph is known and not known to agents in advance. We present algorithms that compute the optimal solutions for a given ring and tree of order $n$, in $O(n)$ time units. For rings in the on-line setting, we give the $2$-competitive algorithm and prove the lower bound of $3/2$ for the competitive ratio for any on-line strategy. For every strategy for trees in the on-line setting, we prove the competitive ratio to be no less than $2$, which can be achieved by the $DFS$ algorithm.Comment: 25 pages, 4 figures, 5 pseudo-code

Highly effective and isotropic pinning in epitaxial Fe(Se,Te) thin films grown on CaF2 substrates

We report on the isotropic pinning obtained in epitaxial Fe(Se,Te) thin films grown on CaF2 (001) substrate. High critical current density values larger than 1 MA/cm2 in self field in liquid helium are reached together with a very weak dependence on the magnetic field and a complete isotropy. Analysis through Transmission Electron Microscopy evidences the presence of defects looking like lattice disorder at a very small scale, between 5 and 20 nm, which are thought to be responsible for such isotropic behavior in contrast to what observed on SrTiO3, where defects parallel to the c-axis enhance pinning in that directio

Radiação solar no sub-bosque de sistema agrossilvipastoril com eucalipto em diferentes arranjos estruturais.

A radiação solar no sub-bosque de povoamentos de eucalipto torna-se decisiva para implantação de culturas intercalares e consórcio com pastagens em sistemas agrossilvipastoris. Objetivou-se determinar a incidência e distribuição da densidade de fluxo de fótons, radiação solar global e iluminância no sub-bosque de diferentes arranjos estruturais de sistema agrossilvipatoril com eucalipto. O experimento foi implantado em dezembro de 1999, em área de cerrado. Realizou-se o plantio de mudas clonais de um híbrido natural de Eucalyptus camaldulensis Dehnh com Eucalyptus urophylla S.T. Blake, em consórcio com arroz no primeiro ano, soja no segundo e pastagem de Brachiaria brizantha (Hochst. ex A. Rich.) Stapf cv. Marandu nos anos consecutivos. O delineamento utilizado foi blocos casualizados em esquema de parcelas subdivididas, com cinco repetições. Nas parcelas, estudou-se o efeito dos arranjos 3,33 x 2 m, 3,33 x 3 m, 5 x 2 m, 10 x 2 m, 10 x 3 m, 10 x 4 m, (3 x 4)+7 m, (3 x 3)+10 m, (3 x 4)+10 m e (3 x 3)+15 m. As subparcelas corresponderam às avaliações na linha e entrelinha de plantio, realizadas aos 27, 38 e 54 meses. A radiação solar no subbosque varia em função dos arranjos. Nos 3,33 x 2 m e 3,33 x 3 m, o fechamento do dossel promove sombreamento geral do sub-bosque aos dois anos. Nos arranjos mais amplos, a distribuição espacial da radiação solar e o sombreamento variam com a época do ano

Produtividade de Brachiaria brizantha (Hochst. ex A. Rich.) Stapf cv. Marandu sob diferentes arranjos estruturais de sistema agrossilvipastoril com eucalipto.

O sucesso de sistemas de produção sustentáveis tem como aspecto fundamental a escolha das espécies. O conhecimento da tolerância da Brachiaria brizantha (Hochst. ex A. Rich.) Stapf ao sombreamento e seu desempenho em consórcio com eucalipto implica na recomendação desta forrageira para implantação de sistemas agrossilvipastoris. O objetivo deste trabalho foi avaliar quantitativa e qualitativamente a produtividade de Brachiaria brizantha (Hochst. ex A. Rich.) Stapf cv. Marandu sob diferentes arranjos estruturais de sistema agrossilvipastoril com eucalipto. Realizou-se o plantio de mudas clonais de um híbrido natural de Eucalyptus camaldulensis Dehnh com Eucalyptus urophylla S.T. Blake, em dezembro de 1999, em área de cerrado, no noroeste deMinas Gerais (Paracatu MG, Brasil). Fez-se o plantio em consórcio com arroz no primeiro ano, soja no segundo e em seguida braquiária, semeada em dezembro de 2001. O experimento foi implantado no delineamento blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições. Nas parcelas foram alocados os arranjos do eucalipto, em linhas duplas: (3 x 3)+10m, (3 x 4)+7 m, (3 x 4)+10 m, (3 x 4)+7+10 m, (3 x 3)+15 m; e linhas simples: 10x3m, e 10x4m. As subparcelas corresponderam às avaliações na linha e na entrelinha de plantio. Foram avaliados o rendimento e aspectos de qualidade da forragem, bem como a densidade de fluxo de fótons fotossinteticamente ativos no subbosque, em cada arranjo. Verificou-se que a forragem disponível (matéria natural e matéria seca) foi sempre maior na entrelinha do que na linha de plantio, independente do arranjo. Os variados arranjos do sistema agrossilvipastoril praticamente não provocaram variação no teor de fibras, N e P na forragem. As concentrações de Ca, K e Mn foram maiores na braquiária sob as linhas de plantio do eucalipto e as oncentrações de Mg e Zn maiores na entrelinha de plantio

A general lower bound for collaborative tree exploration

We consider collaborative graph exploration with a set of $k$ agents. All agents start at a common vertex of an initially unknown graph and need to collectively visit all other vertices. We assume agents are deterministic, vertices are distinguishable, moves are simultaneous, and we allow agents to communicate globally. For this setting, we give the first non-trivial lower bounds that bridge the gap between small ($k \leq \sqrt n$) and large ($k \geq n$) teams of agents. Remarkably, our bounds tightly connect to existing results in both domains. First, we significantly extend a lower bound of $\Omega(\log k / \log\log k)$ by Dynia et al. on the competitive ratio of a collaborative tree exploration strategy to the range $k \leq n \log^c n$ for any $c \in \mathbb{N}$. Second, we provide a tight lower bound on the number of agents needed for any competitive exploration algorithm. In particular, we show that any collaborative tree exploration algorithm with $k = Dn^{1+o(1)}$ agents has a competitive ratio of $\omega(1)$, while Dereniowski et al. gave an algorithm with $k = Dn^{1+\varepsilon}$ agents and competitive ratio $O(1)$, for any $\varepsilon > 0$ and with $D$ denoting the diameter of the graph. Lastly, we show that, for any exploration algorithm using $k = n$ agents, there exist trees of arbitrarily large height $D$ that require $\Omega(D^2)$ rounds, and we provide a simple algorithm that matches this bound for all trees

Development of High Ic Long REBCO Tapes with High Production Rate by PLD Method

AbstractWe have been developing long REBa2Cu3O7-δ coated conductors with high performance by the combination of the IBAD and the PLD methods. To realize the low production cost for REBa2Cu3O7-δ coated conductors, growth conditions were optimized for long tape fabrication in the “in-plume PLD method”. As a result, the Ic performance was confirmed with a high production rate under the high oxygen gas pressure and high laser energy density of > 800 mTorr and > 3J/cm2, respectively. We successfully fabricated a 35 m long GdBa2Cu3O7-δ coated conductor with high Ic value of 619 A/cm-w by the production rate of 30 m/h

SNAI1 expression and the mesenchymal phenotype: an immunohistochemical study performed on 46 cases of oral squamous cell carcinoma

Abstract Background SNAI1 can initiate epithelial-mesenchymal transition (EMT), leading to loss of epithelial characteristics and, in cancer, to invasion and metastasis. We hypothesized that SNAI1 reactivation occurs in oral squamous cell carcinoma (OSCC) where it might also be associated with focal adhesion kinase (FAK) expression and p63 loss. Methods Immunohistochemistry was performed on 46 tumors and 26 corresponding lymph node metastases. Full tissue sections were examined to account for rare and focal expression. Clinical outcome data were collected and analyzed. Results SNAI1-positivity (nuclear, ≥ 5% tumor cells) was observed in 10 tumors and 5 metastases (n = 12 patients). Individual SNAI1(+) tumor cells were seen in primary tumors of 30 patients. High level SNAI1 expression (>10% tumor cells) was rare, but significantly associated with poor outcome. Two cases displayed a sarcomatoid component as part of the primary tumor with SNAI1(+)/FAK(+)/E-cadherin(-)/p63(-) phenotype, but disparate phenotypes in corresponding metastases. All cases had variable SNAI1(+) stroma. A mesenchymal-like immunoprofile in primary tumors characterized by E-cadherin loss (n = 29, 63%) or high cytoplasmic FAK expression (n = 10, 22%) was associated with N(+) status and tumor recurrence/new primary, respectively. Conclusions SNAI1 is expressed, although at low levels, in a substantial proportion of OSCC. High levels of SNAI1 may herald a poor prognosis and circumscribed SNAI1 expression can indicate the presence of a sarcomatoid component. Absence of p63 in this context does not exclude squamous tumor origin. Additional EMT inducers may contribute to a mesenchymal-like phenotype and OSCC progression

The Obesity and Fatty Liver Are Reduced by Plant-Derived Pediococcus pentosaceus LP28 in High Fat Diet-Induced Obese Mice

We evaluated the effect of an oral administration of a plant-derived lactic acid bacterium, Pediococcus pentosaceus LP28 (LP28), on metabolic syndrome by using high fat diet-induced obese mice. The obese mice were divided into 2 groups and fed either a high fat or regular diet for 8 weeks. Each group was further divided into 3 groups, which took LP28, another plant-derived Lactobacillus plantarum SN13T (SN13T) or no lactic acid bacteria (LAB). The lean control mice were fed a regular diet without inducing obesity prior to the experiment. LP28 reduced body weight gain and liver lipid contents (triglyceride and cholesterol), in mice fed a high fat diet for 8 weeks (40%, 54%, and 70% less than those of the control group without LAB, and P = 0.018, P<0.001, and P = 0.021, respectively), whereas SN13T and the heat treated LP28 at 121°C for 15 min were ineffective. Abdominal visceral fat in the high fat diet mice fed with LP28 was also lower than that without LAB by 44%, although it was not significant but borderline (P = 0.076). The sizes of the adipocytes and the lipid droplets in the livers were obviously decreased. A real-time PCR analyses showed that lipid metabolism-related genes, such as CD36 (P = 0.013), SCD1 encoding stearoyl-CoA desaturase 1 (not significant but borderline, P = 0.066), and PPARγ encoding peroxisome proliferator-activated receptor gamma (P = 0.039), were down-regulated by taking LP28 continuously, when compared with those of the control group. In conclusion, LP28 may be a useful LAB strain for the prevention and reduction of the metabolic syndrome