Scaling limit for a drainage network model

We consider the two dimensional version of a drainage network model introduced by Gangopadhyay, Roy and Sarkar, and show that the appropriately rescaled family of its paths converges in distribution to the Brownian web. We do so by verifying the convergence criteria proposed by Fontes, Isopi, Newman and Ravishankar.Comment: 15 page

Scaling Limit and Critical Exponents for Two-Dimensional Bootstrap Percolation

Consider a cellular automaton with state space $\{0,1 \}^{{\mathbb Z}^2}$ where the initial configuration $\omega_0$ is chosen according to a Bernoulli product measure, 1's are stable, and 0's become 1's if they are surrounded by at least three neighboring 1's. In this paper we show that the configuration $\omega_n$ at time n converges exponentially fast to a final configuration $\bar\omega$, and that the limiting measure corresponding to $\bar\omega$ is in the universality class of Bernoulli (independent) percolation. More precisely, assuming the existence of the critical exponents $\beta$, $\eta$, $\nu$ and $\gamma$, and of the continuum scaling limit of crossing probabilities for independent site percolation on the close-packed version of ${\mathbb Z}^2$ (i.e., for independent $*$-percolation on ${\mathbb Z}^2$), we prove that the bootstrapped percolation model has the same scaling limit and critical exponents. This type of bootstrap percolation can be seen as a paradigm for a class of cellular automata whose evolution is given, at each time step, by a monotonic and nonessential enhancement.Comment: 15 page

Produção de mudas de coqueiros, Cocos nucifera L., pelo sistema alternativo.

Apresenta método de produção alternativa de mudas de coqueiro.bitstream/item/81099/1/CPATC-COM.-TEC.-22-98.pd

Variabilidade espacial da textura de dois solos do Deserto Salino, no Estado do Rio Grande do Norte.

Este trabalho teve como objetivo avaliar a variabilidade espacial da textura do solo, em duas áreas do Deserto Salino, na região da planície aluvial do Rio Apodi/Mossoró-RN. Para atingir esse objetivo, utilizaram-se técnicas de geoestatística. As áreas foram georeferenciadas em imagens de satélite (LandSat TM-7), empregandose um GPS portátil. O esquema de amostragem foi ao acaso com 60 unidades amostrais, com volume de 1 dm3, coletadas na camada de 0 a 5 cm. Com exceção do teor de areia grossa no Vertissolo hidromórfico, todos os demais componentes granulométricos, em ambos os solos, apresentaram dependência espacial, sendo o esférico e o exponencial os modelos ajustados aos semivariogramas. O valor do efeito ?pepita? teve pequena contribuição na variância total dos dados e as variáveis apresentaram forte dependência espacial. Houve grande variação na distância até onde as variáveis estudadas apresentaram dependência espacial (alcance), tanto dentro das áreas como entre as áreas estudadas para a maioria das variáveis, indicando que a utilização de um mesmo esquema de amostragem não é apropriado quando se trabalha com muitas variáveis. Por meio dos mapas de ?krigagem?, identificaram-se padrões semelhantes de distribuição espacial para algumas características físicas em função da dinâmica da água

Gamma radiation effects on eggs of Tribolium castaneum (Herbst., 1797) (Coleoptera: Tenebrionidae)

Este trabalho teve por objetivo determinar as doses esterilizantes e letal para ovos de T. castaneum (Herbst., 1797) (Coleoptera: Tenebrionidae), através de doses crescentes de radiação gama. Utilizou-se uma fonte de Cobalto-60, tipo Gammabeam-650, com taxa de dose de 1,28 kGy/hora. O experimento foi conduzido sob condições controladas com temperatura de 25 ± 2°C e umidade relativa de 70 ± 5%. As doses letal e esterilizante para os ovos foram respectivamente 30 e 20 Gy.The objective of this research was to verify the effects of gamma radiation of a Cobalt-60 source on eggs of the red flour beetle Tribolium castaneum (Herbst., 1797). The used dose rate was 1.28 kGy per hour, and the irradiated insects were kept under controlled environment condition: 25 ± 2°C and 70 ± 5% relative humidity. For eggs the sterilizing and lethal dose were respectively, 20 and 30 Gy

Hastings-Levitov aggregation in the small-particle limit

We establish some scaling limits for a model of planar aggregation. The model is described by the composition of a sequence of independent and identically distributed random conformal maps, each corresponding to the addition of one particle. We study the limit of small particle size and rapid aggregation. The process of growing clusters converges, in the sense of Caratheodory, to an inflating disc. A more refined analysis reveals, within the cluster, a tree structure of branching fingers, whose radial component increases deterministically with time. The arguments of any finite sample of fingers, tracked inwards, perform coalescing Brownian motions. The arguments of any finite sample of gaps between the fingers, tracked outwards, also perform coalescing Brownian motions. These properties are closely related to the evolution of harmonic measure on the boundary of the cluster, which is shown to converge to the Brownian web

The impact of the COVID-19 pandemic on the short-term survival of patients with cancer in Northern Portugal

The COVID-19 pandemic led to potential delays in diagnosis and treatment of cancer patients, which may negatively affect the prognosis of these patients. Our study aimed to quantify the impact of COVID-19 on the short-term survival of cancer patients by comparing a period of 4 months after the outbreak began (2 March 2020) with an equal period from 2019. All cancer cases of the esophagus, stomach, colon and rectum, pancreas, lung, skin-melanoma, breast, cervix, and prostate, from the Portuguese Oncology Institute of Porto (IPO-Porto) and diagnosed between 2 March and 1 July of 2019 (before COVID-19) and 2020 (after COVID-19) were identified. Information regarding sociodemographic, clinical and treatment characteristics were collected from the cancer registry database and clinical files. Vital status was assessed to 31 October of the respective years. Cox proportional hazards regression was used to estimate crude and propensity score-adjusted hazards ratio (HR) and 95% confidence intervals (95% CIs) of death. During follow-up to 31 October, there were 154 (11.8%) deaths observed before COVID-19 and 131 (17.2%) after COVID-19, corresponding to crude and adjusted HRs (95% CI) of 1.51 (1.20-1.91) and 1.10 (0.86-1.40), respectively. Significantly higher adjusted hazards of death were observed for patients with Stage III cancer (HR = 2.37; 95% CI: 1.14-4.94) and those undergoing surgical treatment (HR = 3.97; 95% CI: 1.14-13.77) or receiving radiotherapy (HR = 1.96; 95% CI: 1.96-3.74), while patients who did not receive any treatment had a lower mortality hazards (HR = 0.62; 95% CI: 0.46-0.83). The higher overall short-term mortality observed during the COVID-19 pandemic largely reflects the effects of the epidemic on the case-mix of patients being diagnosed with cancer.Funding information: European Regional Development Fund through the Operational Programme Competitiveness and Internationalization & Fundação para a Ciência e a Tecnologia, Grant/Award Number: POCI-01-0145-FEDER-032358; ref. PTDC/SAU-EPI/32358; Fundação para a Ciência e a Tecnologia, Grant/Award Number: info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB/04750/2020/PT; Fundação para a Ciência e a Tecnologia & Agency for Clinical Research and Biomedical Innovation, Grant/Award Number: RESEARCH 4 COVID-19 174_59685054

The impact of the coronavirus disease 2019 pandemic on the diagnosis and treatment of cancer in Northern Portugal

Objectives The coronavirus disease 2019 (COVID-19) pandemic has affected the availability of healthcare resources, and adjustments to cancer care have been necessary considering the risk of morbidity by COVID-19 and of cancer progression. This study aims to quantify the impact of the COVID-19 pandemic on the care of patients with cancer by comparing a period of 4 months after the outbreak began (2 March 2020) with an equal period from 2019. Methods Cancer cases of the esophagus, stomach, colon and rectum, pancreas, lung, skin-melanoma, breast, cervix, prostate, non-Hodgkin lymphoma, and leukemia from the Portuguese Oncology Institute of Porto, and diagnosed between 2 March and 1 July 2019 (before COVID-19) and 2020 (after COVID-19) were identified. Those with the first treatment outside the Portuguese Oncology Institute of Porto were excluded. Sociodemographic, clinical and treatment characteristics were obtained from the cancer registry database and clinical files. Results The absolute number of new cancer cases decreased nearly 40% after the COVID-19 pandemic (from 1430 to 866). The largest decreases were observed for cervical (-74.3%) and prostate (-71.7%) cancers. Cases were more often diagnosed at more advanced stages in 2020 (P = 0.001), and the proportion of patients not starting any treatment until 1 July was just under 20% in 2019 and nearly 40% in 2020. The median times from symptoms onset, first medical exam and first appointment to diagnosis, and from diagnosis to first appointment, multidisciplinary tumor board meeting and first treatment were shorter after COVID-19. Conclusions There was a notable overall decrease in cancer diagnoses after COVID-19, with changes in the characteristics of incident cases. © 2022 Lippincott Williams and Wilkins. All rights reserved.This study was funded by the Foundation for Science and Technology – FCT (Portuguese Ministry of Science, Technology and Higher Education) in collaboration with the Agency for Clinical Research and Biomedical Innovation (AICIB), under the scope of the project “Impacto da pandemia COVID-19 nos cuidados prestados a doentes oncológicos” (Research 4 COVID 174_596850546), and national funding from FCT, under the Unidade de Investigação em Epidemiologia – Instituto de Saúde Pública da Universidade do Porto (EPIUnit; UIDB/04750/2020). SM was funded under the scope of the project “NEON-PC - Neuro-oncological complications of prostate cancer: longitudinal study of cognitive decline” (POCI-01-0145-FEDER-032358; ref. PTDC/SAU-EPI/32358/2017), which is funded by the European Regional Development Fund through the Operational Programme Competitiveness and Internationalization, and national funding from FCT. The funding sources had no involvement in the conduct of the research or preparation of the article