Spatial organization in cyclic Lotka-Volterra systems

We study the evolution of a system of $N$ interacting species which mimics the dynamics of a cyclic food chain. On a one-dimensional lattice with N<5 species, spatial inhomogeneities develop spontaneously in initially homogeneous systems. The arising spatial patterns form a mosaic of single-species domains with algebraically growing size, $\ell(t)\sim t^\alpha$, where $\alpha=3/4$ (1/2) and 1/3 for N=3 with sequential (parallel) dynamics and N=4, respectively. The domain distribution also exhibits a self-similar spatial structure which is characterized by an additional length scale, ${\cal L}(t)\sim t^\beta$, with $\beta=1$ and 2/3 for N=3 and 4, respectively. For $N\geq 5$, the system quickly reaches a frozen state with non interacting neighboring species. We investigate the time distribution of the number of mutations of a site using scaling arguments as well as an exact solution for N=3. Some possible extensions of the system are analyzed.Comment: 18 pages, 10 figures, revtex, also available from http://arnold.uchicago.edu/~ebn

The early Middle Pleistocene archeopaleontological site of Wadi Sarrat (Tunisia) and the earliest record of Bos primigenius

10.1016/j.quascirev.2014.02.01

Avaliação de resultados e financiamento em organizações culturais não-empresariais

Diferentes aspectos relativos à gestão de organizações não empresariais vêm despertando o interesse de gestores e acadêmicos da área de estudos organizacionais. Uma destas questões que merece destaque consiste na busca por financiamento por parte destas organizações e as relações de poder estabelecidas neste processo. Assim, analisam-se neste trabalho os critérios de avaliação de desempenho utilizados por fontes financiadoras de grupos teatrais existentes em Florianópolis - SC. Foram analisadas seis fontes financiadoras: duas públicas, uma para-estatal e três organizações privadas. Investigou-se o processo de financiamento considerando os aspectos: captação dos projetos; exigências das propostas; avaliação das propostas e acompanhamento da execução dos projetos. Com base nos dados observou-se a presença de diversos critérios: qualificação pessoal, controle de despesas, registros internos, qualidade do espetáculo, impactos na sociedade. Critérios explorados pelo SESC despertam a curiosidade por estarem menos relacionados aos processos organizacionais internos, diminuindo possivelmente impactos na estruturação dos grupos em direção ao modelo burocrático

Dihydropyrimidine dehydrogenase pharmacogenetics for predicting fluoropyrimidine-related toxicity in the randomised, phase III adjuvant TOSCA trial in high-risk colon cancer patients

Background: Dihydropyrimidine dehydrogenase (DPD) catabolizes approximately 85% of the administered dose of fluoropyrimidines. Functional DPYD gene variants cause reduced/abrogated DPD activity. DPYD variants analysis may help for defining individual patients' risk of fluoropyrimidine-related severe toxicity. Methods: The TOSCA Italian randomized trial enrolled colon cancer patients for 3 or 6 months of either FOLFOX-4 or XELOX adjuvant chemotherapy. In an ancillary pharmacogenetic study, ten 49 DPYD variants (*2A rs3918290 G>A, *13 rs55886062 T>G, rs67376798 A>T, *4 rs1801158 G>A, *5 rs1801159 A>G, *6 rs1801160 G>A, *9A rs1801265 T>C, rs2297595 A>G, rs17376848 T>C, rs75017182 C>G), were retrospectively tested for associations with > grade 3 fluoropyrimidine-related adverse events (FAEs). An association analysis and a time-to-toxicity (TTT) analysis were planned. To adjust for multiple testing, the Benjamini and Hochberg's False Discovery Rate (FDR) procedure was used. 55 Results: FAEs occurred in 194/508 assessable patients (38.2%). In the association analysis, FAEs 56 occurred more frequently in *6 rs1801160 A allele carriers (FDR=0.0083). At multivariate TTT 57 analysis, significant associations were found for *6 rs1801160 A allele carriers (FDR<0.0001), 58 *2A rs3918290 A allele carriers (FDR <0.0001), rs2297595 GG genotype carriers (FDR=0.0014). 59 Neutropenia was the commonest FAEs (28.5%). *6 rs1801160 (FDR <.0001), and *2A 60 rs3918290 (FDR =0.0004) variant alleles were significantly associated with time to neutropenia. 61 Conclusions: This study adds evidence on the role of DPYD pharmacogenetics for safety of 62 patients undergoing fluoropyrimidine-based chemotherapy