2,392 research outputs found
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T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids.
Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous "half adaptor" (HA), generated by annealing P oligo (carrying a phosphate group at the 5' end) and T oligo (carrying a T-tail at the 3' end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification
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Shape-controlled single-crystal growth of InP at low temperatures down to 220 °C.
III-V compound semiconductors are widely used for electronic and optoelectronic applications. However, interfacing III-Vs with other materials has been fundamentally limited by the high growth temperatures and lattice-match requirements of traditional deposition processes. Recently, we developed the templated liquid-phase (TLP) crystal growth method for enabling direct growth of shape-controlled single-crystal III-Vs on amorphous substrates. Although in theory, the lowest temperature for TLP growth is that of the melting point of the group III metal (e.g., 156.6 °C for indium), previous experiments required a minimum growth temperature of 500 °C, thus being incompatible with many application-specific substrates. Here, we demonstrate low-temperature TLP (LT-TLP) growth of single-crystalline InP patterns at substrate temperatures down to 220 °C by first activating the precursor, thus enabling the direct growth of InP even on low thermal budget substrates such as plastics and indium-tin-oxide (ITO)-coated glass. Importantly, the material exhibits high electron mobilities and good optoelectronic properties as demonstrated by the fabrication of high-performance transistors and light-emitting devices. Furthermore, this work may enable integration of III-Vs with silicon complementary metal-oxide-semiconductor (CMOS) processing for monolithic 3D integrated circuits and/or back-end electronics
The integration of storm water flooding and thermal stress potential in Tainan (Taiwan) and Groningen (Netherlands)
Stormwater flooding and thermal stresses of citizens are two important phenomena for most of the dense urban area. Due to the climate change, these two phenomena will occur more frequently and cause serious problems. Therefore, the sectors for public health and disaster management should be able to assess the vulnerability to stormwater flooding and thermal stress. To achieve this goal, two cities in different climate regions and with different urban context have been selected as the pilot areas, i.eY., Tainan, Taiwan and Groningen, Netherlands. Stormwater flooding and thermal stress maps will be produced for both cities for further comparison. The flooding map indicates vulnerable low lying areas, where the thermal stress map indicates high Physiological Equivalent Temperature (PET) values (thermal comfort) in open areas without shading. The combined map indicates the problem areas of flooding and thermal stress and can be used by urban planners and other stakeholders to improve the living environment
Diagrammatic approach to excitonic effects on nonlinear optical response
Optical responses of atomically thin 2D materials are greatly influenced by
electron-hole interactions. It is by far established that exciton signatures
can be well-identified in the optical absorption spectrum of quasi-2D
materials. However, the same level of understanding of excitonic effects on
nonlinear optical responses and the ability to compute them accurately is still
much desired. Based on the functional integral formalisms and working in the
velocity gauge, we introduce a convenient Feynman diagram approach for
calculating nonlinear responses including excitonic effects. By dressing
electron-photon interactions with electron-hole ladder diagrams, we derive an
expression for second-order optical responses and provide a comprehensive
description of excitonic effects. We apply our approach to a monolayer h-BN
model and show qualitative changes in the second harmonic generation spectrum
when comparing with results assuming independent particles. Our approach can be
readily extended to higher order optical responses and is feasible for
first-principles calculations
Behavior of a coupled arch system
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.Includes bibliographical references (leaves 100-102).by Tzu-Yang Yu.M.Eng
BIOMECHANICAL DIFFERENCES BETWEEN TAI-CHI PRACTICING AND ACTIVE ELDERLY DURING THE STAIR-TO-FLOOR TRANSITION
Long-term Tai-Chi practitioners tend to have similar movement to healthy adults and exhibit movement strategies that reduce fall risk during stair-to-floor transition. We aimed to assess the differences during stair descent to ground in Tai-Chi elderly practitioners and active elderly. Fourteen regular Tai-Chi practitioners and fourteen active elderly participated. Whole-body kinematics and ground reaction forces (GRFs) were recorded synchronously by using motion analysis and a force platform. A t-test was used to test the differences between the groups. Both descent and forward walking step length and center of mass (COM) velocity, both horizontal braking and propulsive force and impulse, ankle range of motion (ROM) and total work in the sagittal plane, and maximum hip moment in the frontal plane had significant differences. Our results appear to support the benefits of long-term Tai-Chi training during the stair-to-floor transition
The Effect of Lexicality, Frequency, and Markedness on Mandarin Tonal Categorization
While the Ganong lexicality effect has been observed for phonemic and tonal categorization, the effects of frequency and markedness are less clear, especially in terms of tonal categorization. In this study, we use Mandarin Chinese to investigate the effects of lexicality, tone frequency and markedness. We examined Mandarin speakers’ tonal categorization of tokens on all possible tonal continua with one end being a word and the other being a tonotactic gap (i.e., an unattested syllable-tone combination). The results of a forced-choice identification experiment showed a general bias against the gap endpoints, with the noted exception of continua involving T4 (X51), the most frequent lexical tone. Specifically, when T4 served as the gap endpoint, no obvious bias against it was observed regardless of its lexical status. Moreover, on the T3–T4 continua, there was an apparent bias against T3 (X214), the tone with the most complex contour, again, regardless of lexicality, suggesting a strong markedness effect. Taken together, the results of this study show the individual effects of lexicality, tone frequency and markedness, as well as their interactions, which contribute to our understanding of tonal categorization in relation to lexical statistics (tone frequency) and phonology (markedness)
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