877 research outputs found
Enzymatic transfer of galactosyl phosphate from UDP-galactose to UDP-N-acetylglucosamine
AbstractThe microsomal fraction of hen oviduct homogenate has been shown to contain an enzyme capable of catalyzing a transfer of galactosyl phosphate from UDP-galactose to UDP-N-acetylglucosamine. The product was isolated and identified as UDP-N-acetylglucosamine-6-phosphogalactose, the same compound as that found as a normal constituent in hen oviduct. The enzyme is analogous in reaction type to UDP-N-acetylglucosamine: glycoprotein N-acetylglucosamine-1-phosphotransferase (the enzyme responsible for introducing the recognition marker of newly synthesized lysosomal enzymes), which suggests that the galactosyl phosphotransferase is involved in galactose 1-phosphate transfer to N-acetylglucosamine residues of a newly synthesized glycoproteins
Advanced aging effects on implicit motor imagery and its links to motor performance: An investigation via mental rotation of letters, hands, and feet
This study focuses on changes in implicit motor imagery during advanced aging and these changes’ co-occurrences with physical motor deficits. We administered a mental rotation (MR) task with letters, hands, and feet to 28 young adults (20–27 years) and to 71 older adults (60–87 years), and assessed motor skills (gait mobility and hand dexterity) and neuropsychological performance. Compared to young adults, older adults showed lower MR performance for all stimuli and stronger biomechanical constraint effects on both hand and foot rotation. Moreover, the foot biomechanical constraint effect continued to increase during late adulthood, and declines in hand and foot motor imagery emerged at earlier old ages than declines in visual imagery. These results first demonstrated distinct aging trajectories of hand motor imagery, foot motor imagery, and visual imagery. Exploratory partial correlation analysis for older adults showed positive associations of low-level perceptual-motor skills (Trail Making Test-A performance) with hand and foot MR performance and positive associations of mobility (Timed Up and Go test performance) with foot and letter MR performance. These associations exhibited somewhat different patterns from those of young adults and raised the possibility that age-related declines in motor (and visual) imagery co-occur with declines in motor functioning
Photothermally controlled Marangoni flow around a micro bubble
We have experimentally investigated the control of Marangoni flow around a micro bubble using photothermal conversion. Using a focused laser spot acting as a highly localized heat source on Au nanoparticles/dielectric/Ag mirror thin film enables us to create a micro bubble and to control the temperature gradient around the bubble at a micrometer scale. When we irradiate the laser next to the bubble, a strong main flow towards the bubble and two symmetric rotation flows on either side of it develop. The shape of this rotation flow shows a significant transformation depending on the relative position of the bubble and the laser spot. Using this controllable rotation flow, we have demonstrated sorting of the polystyrene spheres with diameters of 2 μm and 0.75 μm according to their size
Photoacoustic emission from Au nanoparticles arrayed on thermal insulation layer
Efficient photoacoustic emission from Au nanoparticles on a porous SiO2 layer was investigated experimentally and theoretically. The Au nanoparticle arrays/porous SiO2/SiO2/Ag mirror sandwiches, namely, local plasmon resonators, were prepared by dynamic oblique deposition (DOD). Photoacoustic measurements were performed on the local plasmon resonators, whose optical absorption was varied from 0.03 (3%) to 0.95 by varying the thickness of the dielectric SiO2 layer. The sample with high absorption (0.95) emitted a sound that was eight times stronger than that emitted by graphite (0.94) and three times stronger than that emitted by the sample without the porous SiO2 layer (0.93). The contribution of the porous SiO2 layer to the efficient photoacoustic emission was analyzed by means of a numerical method based on a one-dimensional heat transfer model. The result suggested that the low thermal conductivity of the underlying porous layer reduces the amount of heat escaping from the substrate and contributes to the efficient photoacoustic emission from Au nanoparticle arrays. Because both the thermal conductivity and the spatial distribution of the heat generation can be controlled by DOD, the local plasmon resonators produced by DOD are suitable for the spatio-temporal modulation of the local temperature
Emergence of Asian GAPs and its relationship to global G.A.P.
Global G.A.P. is a one of the most influential private standards in the area of food safety and sustainability. With increasing impacts of Global G.A.P., many Asian countries have introduced the country versions of GAPs; China GAP, Japan GAP, Viet GAP, Thai GAP and ASEAN GAP. Each has been influenced by Global G.A.P. but ways of implementation, implementation bodies as well as focus differ from each other. This paper examines the development and motivation behind how the Asian GAPs have been introduced both from current situation and from historical perspectives. Then we compare current situation of different Asian GAPs
Truly Efficient 2-Round Perfectly Secure Message Transmission Scheme
In the model of perfectly secure message transmission schemes (PSMTs), there are channels between a sender and a receiver. An infinitely powerful adversary \A may corrupt (observe and forge)the messages sent through out of channels. The sender wishes to send a secret to the receiver perfectly privately and perfectly reliably without sharing any key with the receiver.
In this paper, we show the first -round PSMT for such that not only the transmission rate is but also the computational costs of the sender and the receiver are both polynomial in . This means that we solve the open problem raised by
Agarwal, Cramer and de Haan at CRYPTO 2006
Characterization of somatic embryogenesis initiated from the Arabidopsis shoot apex
Somatic embryogenesis is one of the best examples of the remarkable developmental plasticity of plants, in which committed somatic cells can dedifferentiate and acquire the ability to form an embryo and regenerate an entire plant. In Arabidopsis thaliana, the shoot apices of young seedlings have been reported as an alternative tissue source for somatic embryos (SEs) besides the widely studied zygotic embryos taken from siliques. Although SE induction from shoots demonstrates the plasticity of plants more clearly than the embryo-to-embryo induction system, the underlying developmental and molecular mechanisms involved are unknown. Here we characterized SE formation from shoot apex explants by establishing a system for time-lapse observation of explants during SE induction. We also established a method to distinguish SE-forming and non-SE-forming explants prior to anatomical SE formation, enabling us to identify distinct transcriptome profiles of these two explants at SE initiation. We show that embryonic fate commitment takes place at day 3 of SE induction and the SE arises directly, not through callus formation, from the base of leaf primordia just beside the shoot apical meristem (SAM), where auxin accumulates and shoot-root polarity is formed. The expression domain of a couple of key developmental genes for the SAM transiently expands at this stage. Our data demonstrate that SE-forming and non-SE-forming explants share mostly the same transcripts except for a limited number of embryonic genes and root genes that might trigger the SE-initiation program. Thus, SE-forming explants possess a mixed identity (SAM, root and embryo) at the time of SE specification
Almost Secure (1-Round, n-Channel) Message Transmission Scheme
It is known that perfectly secure (-round, -channel) message transmission (MT) schemes exist if and only if ,
where is the number of channels that the adversary can corrupt.
Then does there exist an {\it almost} secure MT scheme for ? In this paper, we first sum up a number flaws of the previous {\it almost} secure MT scheme presented at Crypto 2004. (The authors already noted in thier presentation at Crypto\u272004 that their scheme was flawed.) We next show an equivalence between almost secure MT schemes and secret sharing schemes with cheaters. By using our equivalence, we derive a lower bound on the communication complexity
of almost secure MT schemes. Finally, we present a near optimum scheme which meets our bound approximately. This is the first construction of provably secure almost secure (-round, -channel) MT schemes for
A Chiral Nonracemic Enolate with Dynamic Axial Chirality: Direct Asymmetric Alkylation of α-Amino Acid Derivatives (SYNTHETIC ORGANIC CHEMISTRY-Fine Organic Synthesis)
The structure of enolate was long believed to be achiral. However, a chiral nonracemic enolate with a racemization barrier of 16 kcal/mol at -78 oC was found to be the crucial intermediate for the asymmetric -methylation of 1 to give 2 in 81% ee and 96% yield. The asymmetric -methylation occurs in other amino acid derivatives (Val, Leu, Trp, His, Tyr, Dopa) in 78-93% ee
Tailoring coupling of light to local plasmons by using Ag nanorods/structured dielectric/mirror sandwiches
The optical properties of the sandwich of Ag nanorod array (NRA)/structured dielectric layer/Ag mirror have been investigated theoretically and experimentally, where the structured dielectric layer has stacked sublayers of an anisotropic nanocolumnar layer and a uniform layer. The functions of the nanocolumnar and the uniform sublayers are to control shape of the Ag nanorods and to tune optical path length inside the sandwich, respectively. Calculations based on a simple model by treating the NRAs as uniform effective media indicate that the antireflection condition is realized by changing the thickness of the dielectric layer and that the Ag nanorods absorb most of the incident light. The designed structures have been successfully fabricated by taking advantages of the dynamic oblique-angle deposition technique. Under the experimental antireflection condition, Raman scattering measured on the Ag NRA in the near infrared region exhibits significant enhancement. This indicates that the local electric field close to the Ag nanorods can be controlled by the interference of light in the nanostructured sandwiches
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