Exact results for the Barabasi model of human dynamics

Human activity patterns display a bursty dynamics, with interevent times following a heavy tailed distribution. This behavior has been recently shown to be rooted in the fact that humans assign their active tasks different priorities, a process that can be modeled as a priority queueing system [A.-L. Barabasi, Nature 435, 207 (2005)]. In this work we obtain exact results for the Barabasi model with two tasks, calculating the priority and waiting time distribution of active tasks. We demonstrate that the model has a singular behavior in the extremal dynamics limit, when the highest priority task is selected first. We find that independently of the selection protocol, the average waiting time is smaller or equal to the number of active tasks, and discuss the asymptotic behavior of the waiting time distribution. These results have important implications for understanding complex systems with extremal dynamics.Comment: 4 pages, 4 figures, revte

Role of Activity in Human Dynamics

The human society is a very complex system; still, there are several non-trivial, general features. One type of them is the presence of power-law distributed quantities in temporal statistics. In this Letter, we focus on the origin of power-laws in rating of movies. We present a systematic empirical exploration of the time between two consecutive ratings of movies (the interevent time). At an aggregate level, we find a monotonous relation between the activity of individuals and the power-law exponent of the interevent-time distribution. At an individual level, we observe a heavy-tailed distribution for each user, as well as a negative correlation between the activity and the width of the distribution. We support these findings by a similar data set from mobile phone text-message communication. Our results demonstrate a significant role of the activity of individuals on the society-level patterns of human behavior. We believe this is a common character in the interest-driven human dynamics, corresponding to (but different from) the universality classes of task-driven dynamics.Comment: 5 pages, 6 figures. Accepted by EP

Healthy Pacific Grandparents: A Participatory Action Research Project Exploring Ageing Well Amongst Pacific People in New Zealand

The New Zealand older adult population (aged 65+ years) is growing at a faster rate than the younger population, with many of those in the later years living much longer. The proportion of older Pacific people is forecast to reach 4.1% of the country’s total population within the next two decades, highlighting the importance of research focused on ageing Pacific populations. This article sets out the research protocol and methods for the Pacific Islands Families: Healthy Pacific Grandparents’ Study, which aims to investigate older Pacific people’s viewpoints on ageing to identify specific cultural values, perspectives and understandings as the Pacific population in New Zealand ages. The study will recruit and utilize participants from a grandparent cohort that is nested within the families of the longitudinal Pacific Islands Families Study. This study uses a Participatory Action Research approach to position the participants in a leadership role where they are co-researchers involved in both the research and the implementation of recommendations. Utilizing a transformative research process will bring older Pacific people together to define for themselves their needs and their experiences, identify any areas of shortcoming, and support the implementation of solutions through strategic and informed actions

Uso de sistema de informação para aprimorar o processo de informatização do herbário CNPO da Embrapa Pecuária Sul.

O trabalho objetivou a criação de um método de estruturação dos dados existentes no Herbário CNPO para possibilitar a sua integração ao banco de dados do Sistema de Informação da Biodiversidade Brasileira (SiBBr), bem como realizar o levantamento de Poaceae e Fabaceae inseridas no acervo.Claudia Cristina Gulias Gomes, editora técnica

Manutenção da variabilidade genética de acessos de Bromus auleticus.

Bromus auleticus Trin. ex Nees, cevadilha vacariana, é uma gramínea forrageira nativa considerada de ampla disseminação na América do Sul Temperada, porém de baixa frequência de ocorrência nos campos naturais

Introdução às ciências zootécnica e botânica para alunos do quarto ano em visita à Embrapa Pecuária Sul.

Abstract: Abstract: Research centers are very important to contribute and promote community scientific literacy of children impacts teaching in later grades, promotes the development of conscious citizens regarding the valuation of animal husbandry and food production. Thus, Embrapa has a vital role in society linked to food security through community interaction with agricultural research. The aim of this work was to connect local urban students with animal and botanical sciences and the origin of food, through sensorial and motor skills for a learning associated with daily life. A thematic visit was carried out by 50 students 9-11 years old from the Nossa Senhora Auxiliadora School, Bagé-RS, to Embrapa Southern Livestock, for a variety of forages and ruminants. The children attended the lecture in appropriate language about diet and animal category, different dairy products, animal fat where they saw flipcharts, manipulated dairy packaging, concentrate and roughage ingredients; asked the speakers more than 20 questions. Afterwards, they observed the germoplasm bank: exotic, white clover (Trifolium repens L.), Sudan grass (Sorghum sudanense (Piper) Stapf) BRS Birdsfoot Trefoil (Lotus corniculatus L.) BRS Posteiro; and Herbarium-CNPO with native exsiccates. The high participation of students demonstrated a good receptivity to the actives methodologies.5 p. Zootecnia Brasil 2018

Priority queues with bursty arrivals of incoming tasks

Recently increased accessibility of large-scale digital records enables one to monitor human activities such as the interevent time distributions between two consecutive visits to a web portal by a single user, two consecutive emails sent out by a user, two consecutive library loans made by a single individual, etc. Interestingly, those distributions exhibit a universal behavior, $D(\tau)\sim \tau^{-\delta}$, where $\tau$ is the interevent time, and $\delta \simeq 1$ or 3/2. The universal behaviors have been modeled via the waiting-time distribution of a task in the queue operating based on priority; the waiting time follows a power law distribution $P_{\rm w}(\tau)\sim \tau^{-\alpha}$ with either $\alpha=1$ or 3/2 depending on the detail of queuing dynamics. In these models, the number of incoming tasks in a unit time interval has been assumed to follow a Poisson-type distribution. For an email system, however, the number of emails delivered to a mail box in a unit time we measured follows a powerlaw distribution with general exponent $\gamma$. For this case, we obtain analytically the exponent $\alpha$, which is not necessarily 1 or 3/2 and takes nonuniversal values depending on $\gamma$. We develop the generating function formalism to obtain the exponent $\alpha$, which is distinct from the continuous time approximation used in the previous studies.Comment: 19 pages, 5 figure

Herbário CNPO e Banco Ativo de Germoplasma de Forrageiras do Sul do Brasil: interface para coleta, conservação e informatização.

Resumo.Fernando Flores Cardoso, Daniel Portella Montardo, José Carlos Ferrugem Moraes, Marcos Flávio Silva Borba, Sandro da Silva Camargo, editores técnicos

Manejo de campo nativo e levantamento de espécies em área experimental.

O campo nativo apresenta uma grande diversidade biológica, onde a maioria das espécies encontradas, além de constituir o patrimônio genético do Bioma Pampa, possui bom potencial forrageiro. O objetivo do presente trabalho foi realizar levantamentos de plantas com potencial forrageiro e as indesejáveis ocorrentes na área de estudo, bem como acompanhar a regeneração das espécies do banco de sementes local. O trabalho foi executado na Embrapa Pecuária Sul, Bagé-RS, no potreiro 13 A1, local onde desde a primavera de 2015 realiza-se o acompanhamento da ocorrência de espécies, as quais foram divididas em duas categorias: forrageiras e indesejáveis. Nos períodos setembro de 2015, abril e agosto de 2016 foi realizada a integração lavoura-pecuária (ILP), e o levantamento de espécies em três diferentes estações (primavera-após colheita da soja, em 2015; outono e inverno de 2016). Em 2015 o levantamento apontou que havia predominância de azevém, entretanto, no outono e inverno de 2016 foram identificadas 35 espécies. Na segunda etapa, em 2019, houve predominância significativa na observação de capim-annoni. Por outro lado, ocorreram em menor frequência 25 espécies: seis forrageiras e 19 indesejáveis. Dentre estas, as famílias de maior frequência foram Poaceae, Asteraceae e Fabaceae. Conclui-se que as espécies com bom potencial forrageiro foram regeneradas na área, sendo grande parte delas oriundas do banco de sementes do solo, além de outras plantas semeadas para o melhoramento do campo. Deve-se considerar a necessidade de um melhor acompanhamento da área, quantificando e aprofundando o estudo das espécies