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Opt Lett ; 44(12): 3022-3025, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-31199371


We study optical pulse propagation through a linear, dispersive, gain-loss-assisted bulk medium whose refractive index is time-varying. To analyze the dynamics, we have used a novel technique of time transformation that provides universal formulas of pulse propagation. Our analytical and numerical investigations reveal that optical pulses show asymmetric behavior while propagating in opposite direction through such a medium, in both the temporal and spectral domains. Moreover, the wavelength shift during this process is the most interesting outcome which is limited in range, but could be tuned by varying the refractive index with time. Phenomena that are observed in this Letter are novel and realizable in practical devices such as coupled waveguides where the refractive index is a function of time.

Appl Opt ; 57(25): 7167-7171, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30182976


We report an asymmetric behavior of optical pulses during their propagation through a time-varying linear optical medium. The refractive index of the medium is considered to be varying with time and complex, such that a sufficient amount of gain and loss is present to realize their effect on pulse propagation. We have exploited the universal formula for optical fields in time-varying media. Numerically simulated results reveal that pulses undergo opposite temporal shifts around their initial center position during their bi-directional propagation through the medium along with corresponding spectral shifts. Moreover, the peak power and accumulated chirp (time derivative of accumulated phase) of the output pulse in both propagation directions are also opposite in nature, irrespective of their initial state. Numerically simulated behavior of the pulses agrees well with the analytical solutions.

Indian J Pathol Microbiol ; 54(2): 339-43, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21623086


CONTEXT: Hospital-acquired infections are frequently encountered by the physicians for ailments demanding prolonged hospitalization, especially in intensive care units, where patients are often mechanically ventilated. The organisms most often implicated are bacteria; viral etiology is infrequent. AIMS: The study aims at reviewing lung pathology at autopsy in mechanically ventilated children admitted in pediatric intensive care unit (PICU) to assess the incidence of viral ventilator-associated pneumonias (VAP). SETTING AND DESIGN: Retrospective analysis. MATERIALS AND METHODS: Among the 275 children who had been autopsied, 13 who had been admitted in the PICU satisfied the criteria for VAP. These cases were analyzed on the basis of clinical data and pulmonary pathology. Depending on the overall histology, the cases were classified as being viral or bacterial in etiology. Immunohistochemistry (IHC) for detection of viral antigens was also performed. RESULTS: Of the 13 children, nine (five males and four females) had shown the histomorphologic features, suggesting viral inflammation. The mean age was 33 months. Falling oxygen saturation and increasing respiratory distress had necessitated ventilator support. Acute lymphocytic bronchiolitis, interstitial pneumonitis, diffuse alveolar damage, and necrotizing pneumonia were the histological features. The viruses identified in five patients were adenovirus, respiratory syncytial virus and cytomegalovirus. CONCLUSION: This communication, though not representing the true incidence, emphasizes that a proportion of nosocomial infections is due to viral infections. This should alert the treating intensivists to actively pursue investigations to confirm viral etiology.

Pulmão/patologia , Pulmão/virologia , Pneumonia Associada à Ventilação Mecânica/epidemiologia , Pneumonia Associada à Ventilação Mecânica/virologia , Pneumonia Viral/epidemiologia , Pneumonia Viral/virologia , Adenoviridae/isolamento & purificação , Autopsia , Criança , Pré-Escolar , Citomegalovirus/isolamento & purificação , Feminino , Histocitoquímica , Humanos , Imuno-Histoquímica , Incidência , Lactente , Masculino , Microscopia , Pneumonia Associada à Ventilação Mecânica/patologia , Pneumonia Viral/patologia , Vírus Sinciciais Respiratórios/isolamento & purificação
Br J Nutr ; 105(10): 1520-9, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21272403


Few studies have examined dietary patterns in relation to cardiovascular risk factors in Asian populations, particularly in India. The present study was undertaken to explore dietary patterns in a general urban Bengalee population of women in West Bengal, India, and their association with cardiovascular risk factors. We performed a cross-sectional study of 701 women (aged 35 years and above) selected by cluster sampling from twelve different wards of the Kolkata Municipal Corporation (Kolkata, India). The following three major dietary patterns were identified: the 'vegetable, fruits and pulses' pattern (characterised by higher intakes of dark-yellow and green leafy vegetables, sweets, fruits, pulses, nuts, poultry and eggs, and lower intake of mustard oil); the 'hydrogenated and saturated fat and vegetable oil' pattern (characterised by higher intakes of butter, hydrogenated oil, ghee, vegetable oil, mustard oil, condiments, sweets, fish, high-fat dairy and refined grain); the 'red meat and high-fat dairy' pattern (characterised by higher intakes of red meat, high-fat dairy products, whole grain, high-energy drinks and condiments, and lower intakes of fish, refined grain and low-fat dairy products). The vegetable, fruits and pulses pattern was inversely associated with serum total cholesterol (TC), LDL-cholesterol and non-HDL-cholesterol (HDL-C) concentrations (P < 0·05 for all). The hydrogenated and saturated fat and vegetable oil pattern was positively associated with BMI, waist circumference (WC) and HDL-C concentration (P < 0·05 for all). In this Bengalee population, these three major dietary patterns were observed, and the dietary patterns were independently associated with BMI, WC and serum TC concentrations in women.

Doenças Cardiovasculares/epidemiologia , Dieta , Adulto , Pressão Sanguínea , Índice de Massa Corporal , Doenças Cardiovasculares/fisiopatologia , Feminino , Humanos , Índia/epidemiologia , Estilo de Vida , Pessoa de Meia-Idade , Fatores de Risco , Inquéritos e Questionários