170 research outputs found
Quantifying Fluid Shear Stress in a Rocking Culture Dish
Fluid shear stress (FSS) is an important stimulus for cell functions. Compared with the well established parallel-plate and cone-and-plate systems, a rocking “see-saw” system offers some advantages such as easy operation, low cost, and high throughput. However, the FSS spatiotemporal pattern in the system has not been quantified. In the present study, we developed a lubrication-based model to analyze the FSS distributions in a rocking rectangular culture dish. We identified an important parameter (the critical flip angle) that dictates the overall FSS behaviors and suggested the right conditions to achieving temporally oscillating and spatially relatively uniform FSS. If the maximal rocking angle is kept smaller than the critical flip angle, which is defined as the angle when the fluid free surface intersects the outer edge of the dish bottom, the dish bottom remains covered with a thin layer of culture medium. The spatial variations of the peak FSS within the central 84% and 50% dish bottom are limited to 41% and 17%, respectively. The magnitude of FSS was found to be proportional to the fluid viscosity and the maximal rocking angle, and inversely proportional to the square of the fluid depth-to-length ratio and the rocking period. For a commercial rectangular dish (length of 37.6 mm) filled with ∼2 mL culture medium, the FSS at the center of the dish bottom is expected to be on the order of 0.9 dyn/cm2 when the dish is rocked +5° at 1 cycle/s. Our analysis suggests that a rocking “see-saw” system, if controlled well, can be used as an alternative method to provide low-magnitude, dynamic FSS to cultured cells
Applying Deep Learning to Answer Selection: A Study and An Open Task
We apply a general deep learning framework to address the non-factoid
question answering task. Our approach does not rely on any linguistic tools and
can be applied to different languages or domains. Various architectures are
presented and compared. We create and release a QA corpus and setup a new QA
task in the insurance domain. Experimental results demonstrate superior
performance compared to the baseline methods and various technologies give
further improvements. For this highly challenging task, the top-1 accuracy can
reach up to 65.3% on a test set, which indicates a great potential for
practical use.Comment: To appear in the proceedings of ASRU 201
Ultra-low threshold continuous-wave quantum dot mini-BIC lasers
Highly compact lasers with ultra-low threshold and single-mode continuous
wave (CW) operation have been a long sought-after component for photonic
integrated circuits (PICs). Photonic bound states in the continuum (BICs), due
to their excellent ability of trapping light and enhancing light-matter
interaction, have been investigated in lasing configurations combining various
BIC cavities and optical gain materials. However, the realization of BIC laser
with a highly compact size and an ultra-low CW threshold has remained elusive.
We demonstrate room temperature CW BIC lasers in the 1310 nm O-band wavelength
range, by fabricating a miniaturized BIC cavity in an InAs/GaAs epitaxial
quantum dot (QD) gain membrane. By enabling effective trapping of both light
and carriers in all three dimensions, ultra-low threshold of 12 {\mu}W (0.052
kW/cm^2) is achieved. Single-mode lasing is also realized in cavities as small
as only 5*5 unit-cells (~2.5*2.5 {\mu}m^2 cavity size) with a mode volume of
1.16({\lambda}/n)^3. With its advantages in terms of a small footprint,
ultralow power consumption, robustness of fabrication and adaptability for
integration, the mini-BIC lasers offer a perspective light source for future
PICs aimed at high-capacity optical communications, sensing and quantum
information
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