242 research outputs found

    Racism, Transformation, and Awakeningā€”A Postcolonial Interpretation of Identity in The Grass Is Singing

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    Doris Lessingā€™s ā€œThe Grass Is Singingā€ depicts British expatriatesā€™ migration experiences accommodated into their new living and social surroundings in Southern Rhodesia (now Zimbabwe) to highlight the dilemmatic situation full of shocks and hardships those migrants confronted with in their lives as a result of dynamic colonial identities on African land. The purpose of this paper is to expound on racial discrimination against the native blacks in this novel, analyze the white hostessā€™s identity transformation, and study the nativeā€™s awakening of his ethnic consciousness. Since culture is by no means static, the resilience and adaptability of colonial societies should not be underestimated. Therefore, I argue that through learning how colonized peoples responded to the political and cultural dominance of Europe, the resilience and transformability of colonized cultures would change the characteristics of imperial culture itself in ways that have been both profound and lasting. The themes of racial discrimination, identity transformation, and the awakening of ethnic consciousness depicted in ā€œThe Grass Is Singingā€ continue to have important implications for todayā€™s society

    Visible submicron microdisk lasers

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    The authors describe the performance of submicron microdisk lasers fabricated within InGaP/InGaAlP quantum well material working at room temperature. The smallest lasers, with diameters of approximately 600 nm, feature ultrasmall mode volumes and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 Āµm^3 enable microdisk lasers to be used as spectroscopic sources. Here the authors demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron microdisk lasers

    External modulation method for generating accurate linear optical FMCW

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    Frequency modulation continuous wave (FMCW) lasers are key components in modern optical imaging. However, current intracavity modulation lasers do not exhibit low-frequency jitter rate and high linearity due to the inherent relaxation oscillations. Although this may be compensated in a direct modulation laser diode using an optoelectronic feedback loop, the available sweep speed is moderately small. In this letter, a special external modulation method is developed to improve the performance of FMCW. Since only the first sideband optical field is used during the entire generation process, phase noise is kept to a minimum and is also independent of the sweep speed. We demonstrate that the linearity and jitter rates do not deteriorate appreciably when the sweep speed is changed over three orders of magnitude, even up to the highest sweep speed of 2.5 GHz/ Ī¼s

    Chemical weathering of monsoonal eastern China: implications from major elements of topsoil

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    Major element compositions of 36 bulk samples and 41 clay samples, which were obtained from 47 topsoils collected in monsoonal eastern China, were investigated with conventional wet chemistry and X-ray fluorescence (XRF) spectrometry, respectively. Based on major element analyses, the mobility of major elements and latitudinal distributions of SiO2/Al2O3 ratio, chemical index of alteration (CIA), chemical index of weathering (CIW) and weathering index of Parker (WIP) were analyzed. Meanwhile, the suitability of these chemical weathering indices to topsoils in monsoonal eastern China and its controls were discussed. These investigations indicate that Na, K, Ca, Mg, and Si are relatively depleted, while Mn, P, Fe and Ti are relatively enriched in topsoils of the study area by comparison with their contents in the upper continent crust (UCC), and that alkali metal (Na, K) and alkaline earth metal (Ca, Mg) elements are generally easier to be depleted from their parent materials than other major elements during chemical weathering. The latitudinal distributions of CIA, CIW and WIP show that they are suitable to both bulk and clay samples, but SiO2/Al2O3 is only suitable to clay samples, not suitable in bulk ones. All these investigations indicate a significant dependence of grain-size in major element abundance and latitudinal distributions of SiO2/Al2O3, CIA, CIW and WIP, but parent rock type has little effect on them, except its impact on the latitudinal distribution of WIP in clay samples. The significant grain-size dependence probably indicates the presence of unaltered minerals in bulk samples, thus we suggest that clay samples are more suitable to investigating chemical weathering of sediments on continents than bulk samples. The trivial effect of parent rock type probably indicates a relatively uniform chemical weathering on various parent rocks. Correlation analyses indicate that climate is the dominant control of chemical weathering of topsoils in the study area, and the significant latitude effect indicated by the spatial distributions of chemical weathering indices actually reflect the climate control on chemical weathering of topsoils. Chemical weathering indices actually reflect the integrated weathering history in the study area. Besides the dominant control of climate, other factors like tectonics, parent rock, biology, landform and soil depth and age might also have some effect on the chemical weathering of topsoils in the study area, which needs further research. (C) 2013 Elsevier Ltd. All rights reserved.National Basic Research Program of China [2010CB833405]; National Natural Science Foundation of China [40872111, 40930106

    Visible microdisk and photonic crystals lasers based on InGaP/InGaAlP system

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    We describe the performance of submicron microdisk and photonic crystal lasers fabricated within InGaP/InGaAlP quantum well material. The smallest lasers, with diameters of approximately 600 nm, feature ultra-small mode volumes and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 Ī¼m^3 for microdisk lasers and 0.01 Ī¼m^3 for photonic crystal lasers enable them to be used as spectroscopic sources. Here we demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron mode volume lasers

    Computed Tomography Imaging Features of Pulmonary Sequestration

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    Background: Pulmonary sequestration (PS), generally diagnosed using computed tomography pulmonary angiography (CTPA), is a rare congenital developmental malformation of the lung that is characterized by nonfunctional lung tissue, independent of the normal lung tissue. This paper summarizes the imaging features of the supplying arteries and draining vessels in patients with PS with an aim to assist in timely clinical diagnosis and operation guidance. Materials and Methods: A total of 55 patients with PS diagnosed using CTPA from multiple clinical centers were retrospectively analyzed. Data included demographic characteristics, imaging features, disease location, isolation type, and the features of supplying and draining vessels, as shown on CTPA images. Results: Of the 55 patients reviewed, 3 (5.45%) were children, 3 (5.45%) were adolescents, and 49 (89.09%) were adults; the mean age was 44 years. Fifty-four (98.18%) patients had intralobar sequestration and one (1.82%) had extralobar sequestration. PS was noted 3.5 times more frequently in the left lower lobe than in the right lower lobe. For the supplying arteries, 47 (85.45%) were derived from the descending thoracic aorta, 1 (1.82%) from the abdominal aorta, 7 (12.73%) from the celiac axis, and 1 (1.82%) from the bronchial artery. The draining vessels were the pulmonary veins in 49 patients (89.09%), the umbilical vein in 1 (1.82%), the venae intercostal in 1 (1.82%), the pulmonary arteries in 11 (20.00%), and the vessels were not shown on the images in 2 patients (3.64%). Conclusion: Clinical presentations of PS are non-specific and can be easily missed or misdiagnosed. However, CTPA can help to improve the diagnostic accuracy and identify the supplying arteries and draining vessels, which significantly contribute to surgical planning
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