Power-dependent effective reflection of fiber Bragg grating as output coupler of Ytterbium-doped fiber laser

In this paper, we discuss the effective reflection of a fiber Bragg grating and its dependence on laser power when it is used as an output coupler of an ytterbium-doped fiber laser (here the effective reflection is considered to be a part of intracavity laser power reflected by the grating back to the laser cavity). We propose and discuss an experimental technique based on spectral and power analysis and derive simple formulae that permits one to obtain the intra-cavity power and the grating effective reflection. We show that, due to spectral broadening, the effective reflection dramatically decreases with increasing laser power, the effect precisely fitted using the derived formulae describing this quantity. The experimental part of the present study is based on an analysis of the operational regime of a long-wavelength ytterbium-doped fiber laser

Jovens praticantes de atletismo: contribuição da maturação e variáveis antropométricas no desenvolvimento da força explosiva e velocidade em púberes e pós-púberes durante cinco meses de treinamento

O objetivo do estudo é estimar a contribuição dos estatutos maturacionais, na variação do percentual de gordura, peso e estatura, como também na variação dos desempenhos de força explosiva, força explosiva elástica e força explosiva elástica reflexa e velocidade em jovens atletas de atletismo de ambos os sexos, no período de cinco meses de treinamento. Os atletas foram divididos segundo o sexo e estagio maturacional. Cada jogador foi submetido a uma bateria de testes motores, bem como a avaliação da composição corporal e auto-avaliação de maturação pelo teste de Tanner. Concluiu-se que ocorrem alterações distintas dependendo da variável estudada, gênero e estagio de maturação do atleta. As variáveis antropométricas variaram de acordo com o que ocorre no processo de maturação normal de indivíduos na fase púbere e pós-púberes

Clinical findings and risk factors to oral squamous cell carcinoma in young patients: a 12-year retrospective analysis

Background: In recent years have been observed an increased incidence of OSCC in young individuals. Based on this, the aim this study was to describe the clinical characteristics of all cases of OSCC in younger patients, diagnosed in two oncology referral hospitals, at the northeast region of Brazil within a 12-year period. Material and Methods: Data regarding general characteristics of patients (age, gender and tobacco and/or alcohol habits) and information about the lesions (tumor location, size, regional lymph node metastasis, distant metastasis and clinical stage) were submitted to descriptive and inferential analysis. Statistical analysis included Chi-square and Fisher’s exact tests (P<0.05). Results: Out of 2311 registered cases of OSCC, 76 (3.3%) corresponded to OSCC in patients under 45 years old. Most of them were male (n=62, 81.6%) and tobacco and/or alcohol users (n=40, 52.8%). The most frequent site was the tongue (n=31, 40.8%), with predominance of cases classified at advanced clinical stage (III and IV, n = 46, 60.5%). The advanced stage of OSCC (III and IV) was statistically associated with male gender (P=0.035), lower education level (P=0.007), intraoral sites (P<0.001), presence of pain symptomatology (P=0.006), and consumption of tobacco and/or alcohol (P=0.001). Conclusions: The profile of OSCC in young patients resembles to the commonly characteristics reported for overall population. The late diagnosis in young patients usually results in poor prognosis, associated with gender, harmful habits and tumor location. Although prevalence is low, stimulus to prevention and to early diagnosis should be addressed to young individuals exposed to risk factor

Memória Orgânica: software criado para o ensino de química orgânica

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Ytterbium-doped fiber laser as pulsed source of narrowband amplified spontaneous emission

We report random noise pulsed regime of an ytterbium-doped fiber laser arranged in common Fabry-Perot configuration. We show that the laser output obeys the photon statistics inherent to narrowband amplified spontaneous emission and that the noise pulsing is properly addressed in terms of probability density and autocorrelation functions. Our novel approach reveals, in particular, that the regime’s coherence time dramatically shortens, from few ns to tens ps, with increasing laser power

Ethical dilemmas and validity issues related to the use of new cooling technologies and early recognition of exertional heat illness in sport

The Tokyo 2020 Olympic Games is expected to be among the hottest Games in modern history, increasing the chances for exertional heat stroke (EHS) incidence, especially in non-acclimatised athletes/workers/spectators. The urgent need to recognise EHS symptoms to protect all attendees'' health has considerably accelerated research examining the most effective cooling strategies and the development of wearable cooling technology and real-time temperature monitoring. While these technological advances will aid the early identification of EHS cases, there are several potential ethical considerations for governing bodies and sports organisers. For example, the impact of recently developed cooling wearables on health and performance is unknown. Concerning improving athletic performance in a hot environment, there is uncertainty about this technology''s availability to all athletes. Furthermore, the real potential to obtain real-time core temperature data will oblige medical teams to make crucial decisions around their athletes continuing their competitions or withdraw. Therefore, the aim of this review is (1) to summarise the practical applications of the most novel cooling strategies/technologies for both safety (of athletes, spectators and workers) and performance purposes, and (2) to inform of the opportunities offered by recent technological developments for the early recognition and diagnosis of EHS. These opportunities are presented alongside several ethical dilemmas that require sports governing bodies to react by regulating the validity of recent technologies and their availability to all

Impact of the anatomical location, alcoholism and smoking on the prevalence of advanced oral cancer in Brazil

To evaluate the prevalence of oral cancer in Brazil according to the clinical stage, anatomical location, alcoholism and smoking. Data referring to 31,217 cases of oral cancer, from 2000 to 2010, were obtained from the Integrator Module of the Hospital Registry of Cancer. Inconsistent data (?non-classified? cases) was eliminated and 21,160 cases were analyzed. The frequency distribution according to clinical stage, anatomical location, alcoholism and smoking was analyzed descriptively and through a binary logistic regression model (?<0.05). The clinical stage (dependent variable) was dichotomized in early stage (I and II) or advanced stage (III and IV). The year of diagnosis, anatomical location and deleterious habits (alcoholism and smoking) were considered independent variables. The most frequent characteristics were: oropharynx location (n=3856, 18.41%), clinical stage IV (n=11924, 56.09%) and combined use of alcohol and tobacco (n=19226; 61.59%). The year 2009 (p<0.01, PR = 1.162, CI-95%=1.053-1.283) and location at the base of tongue (p<0.01, PR = 2.485, CI-95% = 2.182-2.807) presented a higher prevalence ratio for advanced stage oral cancer. The combined use of alcohol and tobacco showed a higher prevalence rate for the advanced clinical stage of cancer (p<0.01, PR =1.449, CI-95%=1.382-1.520) if compared to individuals without habits, or just alcoholics. Higher prevalence of advanced stage of oral cancer is related to the localization at the base of the tongue and to the concomitant use of alcohol and tobacco. Therefore, it can be suggested that all these characteristics lead to a worse prognosis of oral cancer