Microfluidic-based measurement of erythrocyte sedimentation rate for biophysical assessment of blood in an in vivo malaria-infected mouse     

Yang Jun Kang  Young-Ran Ha  Sang-Joon Lee 《Biomicrofluidics》2014,8(4)

This study suggests a new erythrocyte sedimentation rate (ESR) measurement method for the biophysical assessment of blood by using a microfluidic device. For an effective ESR measurement, a disposable syringe filled with blood is turned upside down and aligned at 180° with respect to gravitational direction. When the blood sample is delivered into the microfluidic device from the top position of the syringe, the hematocrit of blood flowing in the microfluidic channel decreases because the red blood cell-depleted region is increased from the top region of the syringe. The variation of hematocrit is evaluated by consecutively capturing images and conducting digital image processing technique for 10 min. The dynamic variation of ESR is quantitatively evaluated using two representative parameters, namely, time constant (λ) and ESR-area (A_ESR). To check the performance of the proposed method, blood samples with various ESR values are prepared by adding different concentrations of dextran solution. λ and A_ESR are quantitatively evaluated by using the proposed method and a conventional method, respectively. The proposed method can be used to measure ESR with superior reliability, compared with the conventional method. The proposed method can also be used to quantify ESR of blood collected from malaria-infected mouse under in vivo condition. To indirectly compare with the results obtained by the proposed method, the viscosity and velocity of the blood are measured using the microfluidic device. As a result, the biophysical properties, including ESR and viscosity of blood, are significantly influenced by the parasitemia level. These experimental demonstrations support the notion that the proposed method is capable of effectively monitoring the biophysical properties of blood.  相似文献   

Darwin’s Difficulties and Students’ Struggles with Trait Loss: Cognitive-Historical Parallelisms in Evolutionary Explanation     

Minsu Ha  Ross H. Nehm 《Science & Education》2014,23(5):1051-1074

Although historical changes in scientific ideas sometimes display striking similarities with students’ conceptual progressions, some scholars have cautioned that such similarities lack meaningful commonalities. In the history of evolution, while Darwin and his contemporaries often used natural selection to explain evolutionary trait gain or increase, they struggled to use it to convincingly account for cases of trait loss or decrease. This study examines Darwin’s evolutionary writings about trait gain and loss in the Origin of Species (On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. D. Appleton, New York, 1859) and compares them to written evolutionary explanations for trait gain and loss in a large (n > 500), cross-cultural and cross-sectional sample (novices and experts from the USA and Korea). Findings indicate that significantly more students and experts applied natural selection to cases of trait gain, but like Darwin and his contemporaries, they more often applied ‘use and disuse’ and ‘inheritance of acquired characteristics’ to episodes of trait loss. Although the parallelism between Darwin’s difficulties and students’ struggles with trait loss are striking, significant differences also characterize explanatory model structure. Overall, however, students and scientists struggles to explain trait loss—which is a very common phenomenon in the history of life—appear to transcend time, place, and level of biological expertise. The significance of these findings for evolution education are discussed; in particular, the situated nature of biological reasoning, and the important role that the history of science can play in understanding cognitive constraints on science learning.  相似文献   

微机内存管理机制的分析及优化配置     

哈贵庭 《宁夏师范学院学报》1998,19(3):13-17

从硬件和软件两个方面分析微机内部存储器的构原理及管理机制,讨论微机单机,网络工作站的内存配置的几个重要问题。  相似文献   

How online usage of subscription‐based journalism and mass communication research journal articles predicts citations          下载免费PDF全文

Louisa Ha  Weiwei Jiang  Chang Bi  Ruonan Zhang  Tao Zhang  Xiaoli Wen 《Learned Publishing》2016,29(3):183-192

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