A Lei de ZIPF ou Regra 80/20 da Internet

As Leis de Potência, LP, (Power Laws, em inglês), Leis de Pareto ou Leis de Zipf são distribuições estatísticas, com inúmeras aplicações práticas, em sistemas naturais e artificiais. Alguns exemplos são a variação dos rendimentos pessoais ou de empresas, a ocorrência de palavras em textos, as repetições de sons ou conjuntos de sons em composições musicais, o número de vítimas em guerras ou outros cataclismos, a magnitude de tremores de terra, o número de vendas de livros ou CD’s na internet, o número de sítios mais acedidos na Internet, entre muitos outros. Vilfredo Pareto (1897-1906) afirma, no manual de economia política “Cours d’Economie Politique”, que grande parte da economia mundial segue uma determinada distribuição, em que 20% da população reúne 80% da riqueza total do país, estando, assim uma pequena fração da sociedade a controlar a maior fatia do dinheiro. Isto resume o comportamento de uma variável que segue uma distribuição de Pareto (ou Lei de Potência). Neste trabalho pretende-se estudar em pormenor a aplicação das leis de potência a fenómenos da internet, como sendo o número de sítios mais visitados, o número de links existentes em determinado sítio, a distribuição de nós numa rede da internet, o número livros vendidos e as vendas em leilões online. Os resultados obtidos permitem-nos concluir que todos os dados estudados são bem aproximados, numa escala logarítmica, por uma reta com declive negativo, seguindo, assim, uma distribuição de Pareto. O desenvolvimento e crescimento da Web, tem proporcionado um aumento do número dos utilizadores, conteúdos e dos sítios. Grande parte dos exemplos presentes neste trabalho serão alvo de novos estudos e de novas conclusões. O fato da internet ter um papel preponderante nas sociedades modernas, faz com que esteja em constante evolução e cada vez mais seja possível apresentar fenómenos na internet associados Lei de Potência.Power laws are statistical distributions. They have been applied to the modeling of various phenomena of everyday life. Some examples are the variation in personal incomes or businesses, the occurrence of words in texts, the repetition of sounds or combinations of sounds in musical compositions, the number of casualties in wars or other cataclysms, the magnitude of earthquakes, the number of sales of books or CD's on the internet, the number of sites on the Internet, among many others. Vilfredo Pareto (1897-1906) states, in his manual of political economy, "Cours d'Economie Politique", that a large part of the world economy follows a particular distribution, in which 20% of the population gathers 80% of the total wealth, and so, a small fraction of the society controls the largest share of the money. This summarizes the behavior of a variable that follows a Pareto distribution (or, Power Law). This work intends to study in detail the application of power laws (PL) to the internet phenomena, for example, the number of top sites, the number of links on a particular site, the distribution of internet nodes, the number of books sold online, online auctions. The results obtained allow us to conclude that all data studied are well approximate, on a logarithmic scale, by a straight line with a negative slope, thus following a Pareto distribution. The development and growth of the Web, has provided an increasing number of users, content and sites. Most of the examples in this work will be the target of new studies and new findings. The fact that the internet has a preponderant role in modern societies, forces its constant evolution and increasing, and it is possible that new internet phenomena associated with PL may appear

SPRINT: Optimization of Staff Management for Desk Customer Relations Services at Hera

In this paper, we discuss a decision support system for optimizing staff management of desk customer relations services at Hera, a large Italian multiutility company. The system, SPRINT, which is based on state-of-the-art demand forecasting, implements a novel two-phase optimization procedure based on adaptive staffing. The processes developed proved to be superior to other state-of-the-art approaches. After using the system for two years, Hera has considerably improved its planning and management processes, achieved a significant level-of-service improvement of its desk customer services, and substantially increased staff productivity

Statin use and survival in patients with metastatic castrationresistant prostate cancer treated with abiraterone or enzalutamide after docetaxel failure: The international retrospective observational STABEN study

Background: Statins may potentiate the effects of anti-hormonal agents for metastatic castration-resistant prostate cancer (mCRPC) through further disruption of essential steroidogenic processes. We investigated the effects of statin use on clinical outcomes in patients with mCRPC receiving abiraterone or enzalutamide. Materials and methods: This was a retrospective multicenter study including patients that received abiraterone or enzalutamide for mCRPC. The effect of concurrent statin use on outcomes was evaluated. The associations of statins with early (=12 weeks) prostate-specific antigen (PSA) declines (> 30%), cancer-specific survival and overall survival (OS) were evaluated after controlling for known prognostic factors. Results: Five hundred and ninety-eight patients treated with second-line abiraterone or enzalutamide after docetaxel for mCRPC were included. A total of 199 men (33.3%) received statins during abiraterone/enzalutamide treatment. Median OS was 20.8 months (95% CI = 18.3-23.2) for patients who received statins, versus 12.9 months (95% CI = 11.4-14.6) for patients who did not receive statins (P < 0.001). After adjusting for age, alkaline phosphatase, PSA, neutrophil-to-lymphocytes ratio, Charlson comorbidity score, Gleason score, visceral disease, hemoglobin, opiate use and abiraterone versus enzalutamide treatment, the use of statin therapy was associated with a 53% reduction in the overall risk of death (hazard ratio [HR] = 0.47; 95% CI = 0.35-0.63; P < 0.001). Statin use was also associated with a 63% increased odds of a > 30% PSA decline within the first 12 weeks of treatment (OR = 1.63; 95% CI = 1.03-2.60; P = 0.039). Conclusions: In this retrospective cohort, statin use was significantly associated with both prolonged OS and cancer-specific survival and increased early > 30% PSA declines. Prospective validation is warranted

Impact of COVID-19 outbreak on cancer immunotherapy in Italy: a survey of young oncologists

The coronavirus disease 2019 (COVID-19) pandemic has overwhelmed the health systems worldwide. Data regarding the impact of COVID-19 on cancer patients (CPs) undergoing or candidate for immune checkpoint inhibitors (ICIs) are lacking. We depicted the practice and adaptations in the management of patients with solid tumors eligible or receiving ICIs during the COVID-19 pandemic, with a special focus on Campania region

Impact of COVID-19 outbreak on cancer immunotherapy in Italy: a survey of young oncologists

Background The coronavirus disease 2019 (COVID-19) pandemic has overwhelmed the health systems worldwide. Data regarding the impact of COVID-19 on cancer patients (CPs) undergoing or candidate for immune checkpoint inhibitors (ICIs) are lacking. We depicted the practice and adaptations in the management of patients with solid tumors eligible or receiving ICIs during the COVID-19 pandemic, with a special focus on Campania region. Methods This survey (25 questions), promoted by the young section of SCITO (Societa Campana di ImmunoTerapia Oncologica) Group, was circulated among Italian young oncologists practicing in regions variously affected by the pandemic: high (group 1), medium (group 2) and low (group 3) prevalence of SARS-CoV-2-positive patients. For Campania region, the physician responders were split into those working in cancer centers (CC), university hospitals (UH) and general hospitals (GH). Percentages of agreement, among High (H) versus Medium (M) and versus Low (L) group for Italy and among CC, UH and GH for Campania region, were compared by using Fisher's exact tests for dichotomous answers and chi(2)test for trends relative to the questions with 3 or more options. Results This is the first Italian study to investigate the COVID-19 impact on cancer immunotherapy, unique in its type and very clear in the results. The COVID-19 pandemic seemed not to affect the standard practice in the prescription and delivery of ICIs in Italy. Telemedicine was widely used. There was high consensus to interrupt immunotherapy in SARS-CoV-2-positive patients and to adopt ICIs with longer schedule interval. The majority of the responders tended not to delay the start of ICIs; there were no changes in supportive treatments, but some of the physicians opted for delaying surgeries (if part of patients' planned treatment approach). The results from responders in Campania did not differ significantly from the national ones. Conclusion Our study highlights the efforts of Italian oncologists to maintain high standards of care for CPs treated with ICIs, regardless the regional prevalence of COVID-19, suggesting the adoption of similar solutions. Research on patients treated with ICIs and experiencing COVID-19 will clarify the safety profile to continue the treatments, thus informing on the most appropriate clinical conducts