ABSTRACT Abnormal multiplication of oral bacteria causes dental caries and dental plaque. These diseases continue to be major public health concerns worldwide, mainly in developing countries. In this study, the chemical composition and antimicrobial activity of the essential oil of Vitex agnus-castus leaves (VAC‒EO) collected in the North of Brazil against a representative panel of cariogenic bacteria were investigated. The antimicrobial activity of VAC-EO was evaluated in terms of its minimum inhibitory concentration (MIC) values by using the broth microdilution method in 96-well microplates. The chemical constituents of VAC-EO were identified by gas chromatography (GC‒FID) and gas chromatography‒mass spectrometry (GC‒MS). VAC‒EO displayed some activity against all the investigated oral pathogens; MIC values ranged from 15.6 to 200 μg/mL. VAC-EO had promising activity against Streptococcus mutans (MIC= 15.6 μg/mL), Lactobacillus casei (MIC= 15.6 μg/mL), and Streptococcus mitis (MIC= 31.2 μg/mL). The compounds 1,8-cineole (23.8%), (E)-β-farnesene (14.6%), (E)-caryophyllene (12.5%), sabinene (11.4%), and α-terpinyl acetate (7.7%) were the major chemical constituents of VAC‒EO. VAC-EO displays antimicrobial activity against cariogenic bacteria. The efficacy of VAC-EO against S. mutans is noteworthy and should be further investigated.

Apresentamos nesse trabalho, um experimento realizado nos Laboratórios didáticos do Instituto de Física da USP, relacionado ao estudo do funcionamento de filtros RC para baixas e altas freqüências. Para tal, foi especialmente projetado um circuito que efetua a superposição de um sinal gerado internamente, a uma onda senoidal externa. Várias situações experimentais podem ser geradas, por meio da variação da freqüência, tanto do sinal interno quanto da onda senoidal externa. Um estudo das componentes de freqüência de Fourier é também realizado para se estabelecer os parâmetros de funcionamento dos filtros. O funcionamento dos circuitos como integradores e diferenciadores também é explorado. Os estudantes são, portanto, levados a compreender a eficácia desses filtros mais simples, dependendo das freqüências dos sinais de entrada e correspondentes componentes de Fourier, e das freqüências de corte estabelecidas.

In this work we present an experiment performed in the undergraduate laboratories at the University of São Paulo Physics Institute. It is related to the study of low-pass and high-pass RC filters. For this purpose, we designed and constructed a circuit for the superposition of an internally generated signal and an external sinusoidal signal. An investigation of the Fourier frequency components is also performed in order to establish working parameters for the RC filters. The operation of the circuits as integrators and differentiators is also explored. The students are therefore led to understand how efficient these circuits can be depending on the frequency and Fourier components of the entrance signals, as well as the cutoff frequencies previously defined.

Neste trabalho é discutida a validade da aproximação de lente fina em atividades experimentais que envolvem a determinação de distâncias focais. É utilizado o formalismo matricial para o estudo de trajetória de raios luminosos através de um sistema de lentes espessas, sendo introduzido o conceito de planos principais. Nesse contexto, é mostrado que para uma lente espessa típica utilizada nos laboratórios didáticos do Instituto de Física da USP, a aproximação de lente fina não é adequada.

In this work we discuss the validity of the thin-lens approximation in experiments for focal distance determination. We use the matrix formalism for the study of ray trajectories through a thick lens system and introduce the concept of principal planes. It is shown that for a typical lens used in the undergraduate laboratory at the University of São Paulo Physics Institute, the thin lens approximation is not valid.

Fusion cross section excitation functions were measured for the 6;7Li+59Co systems (12 < Elab < 26 MeV)aiming the investigation of the effect of the breakup process on the fusion cross section. The experimental method consisted on the detection of gamma-rays from the evaporation residues. Coupled channels calculations have been performed for both systems. The comparison to the experimental results support the conclusion that there is neither supression nor enhancement at energies above the coulomb barrier. A slight enhancement at energies below the barrier is observed for the 6Li+59Co cross section over the one for 7Li+59Co. In order to better quantify the effect of the breakup process, coincidence measurements for the breakup products are being performed.

A hipertensão arterial é um dos principais fatores de risco para acidentes vasculares encefálicos. No entanto, o tratamento agressivo da hipertensão na fase aguda pode estar associada a pior evolução clínica. Apresentamos o caso de uma paciente de 81 anos, admitida após múltiplos infartos encefálicos em circulação posterior. Em vigência de anticoagulação plena, a paciente apresentou deterioração neurológica coincidindo com normalização dos níveis pressóricos. Uma angiorressonância documentou uma estenose vertebral bilateral. Após indução de hipertensão com dopamina, a paciente apresentou rápida melhora dos déficits. Nesse primeiro relato de hipertensão induzida na literatura brasileira, ilustramos o potencial benefício dessa estratégia terapêutica em pacientes com documentado mecanismo hemodinâmico de piora clínica.

Hypertension is one of the main risk factors for stroke. However, treating hypertension in the acute phase may cause further neurological deterioration. We present a case of an 81-year-old woman, admitted after multiple infarcts in the posterior circulation. While fully anticoagulated, her neurological deficits worsened, coinciding with normalization of her blood pressure levels. Magnetic resonance angiography documented bilateral vertebral artery stenoses. Induced hypertension was followed by rapid clinical improvement. In this first report of induced hypertension in the Brazilian literature, we illustrate the potencial benefit of this therapeutic strategy in patients with documented hemodynamic mechanism of clinical deterioration.