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Search Results: 1 - 10 of 490477 matches for " Jason S.-C Chien "
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RNAi, DRD1, and Histone Methylation Actively Target Developmentally Important Non-CG DNA Methylation in Arabidopsis
Simon W.-L Chan,Ian R Henderson,Xiaoyu Zhang,Govind Shah,Jason S.-C Chien,Steven E Jacobsen
PLOS Genetics , 2006, DOI: 10.1371/journal.pgen.0020083
Abstract: Cytosine DNA methylation protects eukaryotic genomes by silencing transposons and harmful DNAs, but also regulates gene expression during normal development. Loss of CG methylation in the Arabidopsis thaliana met1 and ddm1 mutants causes varied and stochastic developmental defects that are often inherited independently of the original met1 or ddm1 mutation. Loss of non-CG methylation in plants with combined mutations in the DRM and CMT3 genes also causes a suite of developmental defects. We show here that the pleiotropic developmental defects of drm1 drm2 cmt3 triple mutant plants are fully recessive, and unlike phenotypes caused by met1 and ddm1, are not inherited independently of the drm and cmt3 mutations. Developmental phenotypes are also reversed when drm1 drm2 cmt3 plants are transformed with DRM2 or CMT3, implying that non-CG DNA methylation is efficiently re-established by sequence-specific signals. We provide evidence that these signals include RNA silencing though the 24-nucleotide short interfering RNA (siRNA) pathway as well as histone H3K9 methylation, both of which converge on the putative chromatin-remodeling protein DRD1. These signals act in at least three partially intersecting pathways that control the locus-specific patterning of non-CG methylation by the DRM2 and CMT3 methyltransferases. Our results suggest that non-CG DNA methylation that is inherited via a network of persistent targeting signals has been co-opted to regulate developmentally important genes.
The legitimate scientific name of the valuable medicinal mushroom "Niu-Chang- Chih" known only from Taiwan
S.-C. Jong
Micología Aplicada Internacional , 2012,
Abstract: "Niu-Chang-Chih" is a valuable medicinal mushroom known only from Taiwan. It has long been used in folk medicine as an antidote for alcohol and drug intoxication, as an anticancer agent in liver cancer and in the treatment of diarrhea, abdominal pain, hypertension and skin itching. The pharmacological activities and the chemical constituents of crude extract of "Niu-Chang-Chih" are quite different from those reported for 'Linzhi" (Ganoderma lucidum ). Thus, a legitimate scientific name for the mushroom is essential for health, trade, conservation, property rights protection, and data retrieval systems. The esirability for use of a legitimate name is not only evident, but such use is becoming increasingly urgent with wider recognition of the important role the mushroom plays in bioindustry and biotechnology. There are four scientific names related to the mushroom "Niu-Chang-Chih" in the commercial and scientific literature: Ganoderma camphoratum Zang et Su, 1990; Antrodia cinnamomea Chang et Chou, 1995; Antrodia camphorata (Zang et Su) Wu et al., 1997; and Taiwanofungus camphoratus (Zang et Su) Wu et al., 2004. In order to determine the legitimate name from those cited for the mushroom, the nomenclatural standing with regard to legitimacy of each name is critically reviewed in accordance with particular rules of the international Code of Nomenclature for algae, fungi, and plants (ICN, the Melbourne Code of 2011). Clearly they all are effectively and validly published names. However, the name G. camphoratum is legitimate for a "Linzhi" mushroom, but illegitimate for the "Niu-Chang-Chih" mushroom because it is based on a mixed nomenclatural type (HKAS 22294) with two taxonomically discordant elements. The echinulate Ganoderma spore element of the mixed holotype HKAS 22294 was later separated and designated as lectotype of G. camphoratum by Chang and Chou in 2004. In addition, the new combinations A. camphorata (1997) and T. camphoratus (2004) were superfluous names for A. cinnamomea (1995) when published and must be rejected because the name A. cinnamomea was readily available. Each mushroom can bear only one legitimate name and any name that is contrary to rules of the ICN must be rejected unless conserved or sanctioned by the International Botanical Congress. Consequently, A. cinnamomea is the only "legitimate" name now available for the mushroom "Niu- Chang-Chih" with the holotype TFRI 119. It is thus incorrect (wrong) to cite these illegitimate names A. camphorata and T. camphoratus as taxonomic synonyms of the legitimate name A. cinnamomea. Unfortunat
Scattering by closely spaced infinite cylinders in an absorbing medium
S.-C. Lee
Atti della Accademia Peloritana dei Pericolanti : Classe di Scienze Fisiche, Matematiche e Naturali , 2011, DOI: 10.1478/c1v89s1p055
Abstract: Scattering by closely spaced parallel infinite cylinders in an absorbing medium is considered in this paper. The source wave is arbitrarily polarized and propagates in a general direction at the cylinders. The formulation utilizes the Hertz potential approach, and the scattering cross section and intensity distribution in the far-field are developed. Numerical results are presented to illustrate the influence of the absorbing medium on the scattering properties of two configurations of closely-spaced cylinders.
Secure Multiparty Computation between Distrusted Networks Terminals
S.-C. S. Cheung,Thinh Nguyen
EURASIP Journal on Information Security , 2007, DOI: 10.1155/2007/51368
Abstract: One of the most important problems facing any distributed application over a heterogeneous network is the protection of private sensitive information in local terminals. A subfield of cryptography called secure multiparty computation (SMC) is the study of such distributed computation protocols that allow distrusted parties to perform joint computation without disclosing private data. SMC is increasingly used in diverse fields from data mining to computer vision. This paper provides a tutorial on SMC for nonexperts in cryptography and surveys some of the latest advances in this exciting area including various schemes for reducing communication and computation complexity of SMC protocols, doubly homomorphic encryption and private information retrieval.
Static and temporal gravity field recovery using grace potential difference observables
S.-C. Han, C. Jekeli,C. K. Shum
Advances in Geosciences (ADGEO) , 2003,
Abstract: The gravity field dedicated satellite missions like CHAMP, GRACE, and GOCE are supposed to map the Earth’s global gravity field with unprecedented accuracy and resolution. New models of Earth’s static and time-variable gravity field will be available every month as one of the science products from GRACE. Here we present an alternative method to estimate the gravity field efficiently using the in situ satellite-to-satellite observations at the altitude and show results on static as well as temporal gravity field recovery. Considering the energy relation between the kinetic energy of the satellite and the gravitational potential, the disturbing potential difference observations can be computed from the orbital parameter vectors in the inertial frame, using the high-low GPS-LEO GPS tracking data, the low-low satelliteto- satellite GRACE measurements, and data from 3-axis accelerometers (Jekeli, 1999). The disturbing potential observation also includes other potentials due to tides, atmosphere, other modeled signals (e.g. N-body) and the geophysical fluid signals (hydrological and oceanic mass variations), which should be recoverable from GRACE mission with a monthly resolution. The simulation results confirm that monthly geoid accuracy is expected to be a few cm with the 160 km resolution (up to degree and order 120) once other corrections are made accurately. The time-variable geoids (ocean and ground water mass) might be recovered with a noise-to-signal ratio of 0.1 with the resolution of 800 km every month assuming no temporal aliasing. Key words. GRACE mission, Energy integral, Geopotential, Satellite-to-satellite tracking, Temporal gravity field
Chemical characterization and source apportionment of PM2.5 in Beijing: seasonal perspective
R. Zhang,J. Jing,J. Tao,S.-C. Hsu
Atmospheric Chemistry and Physics Discussions , 2013, DOI: 10.5194/acpd-13-9953-2013
Abstract: In this study, 121 daily PM2.5 (aerosol particle with aerodynamic diameter less than 2.5 μm) samples were collected from an urban site in Beijing in four months between April 2009 and January 2010 representing the four seasons. The samples were determined for various compositions, including elements, ions, and organic/elemental carbon. Various approaches, such as chemical mass balance, positive matrix factorization (PMF), trajectory clustering, and potential source contribution function (PSCF), were employed for characterizing aerosol speciation, identifying likely sources, and apportioning contributions from each likely source. Our results have shown distinctive seasonalities for various aerosol speciations associated with PM2.5 in Beijing. Soil dust waxes in the spring and wanes in the summer. Regarding the secondary aerosol components, inorganic and organic species may behave in different manners. The former preferentially forms in the hot and humid summer via photochemical reactions, although their precursor gases, such as SO2 and NOx, are emitted much more in winter. The latter seems to favorably form in the cold and dry winter. Synoptic meteorological and climate conditions can overwhelm the emission pattern in the formation of secondary aerosols. The PMF model identified six main sources: soil dust, coal combustion, biomass burning, traffic and waste incineration emission, industrial pollution, and secondary inorganic aerosol. Each of these sources has an annual mean contribution of 16, 14, 13, 3, 28, and 26%, respectively, to PM2.5. However, the relative contributions of these identified sources significantly vary with changing seasons. The results of trajectory clustering and the PSCF method demonstrated that regional sources could be crucial contributors to PM pollution in Beijing. In conclusion, we have unraveled some complex aspects of the pollution sources and formation processes of PM2.5 in Beijing. To our knowledge, this study is the first systematical study that comprehensively explores the chemical characterizations and source apportionments of PM2.5 aerosol speciation in Beijing by applying multiple approaches based on a completely seasonal perspective.
A new non-uniform blast load model for SDOF method of one-way reinforced concrete slab
Wang W.,Zhang D.,Lu F.,Wang S.-C.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122604016
Abstract: A new effective model for calculation of the equivalent uniform blast load for non-uniform blast load such as close-in explosion of a one-way square and rectangle reinforced concrete slab is proposed in this paper. The model is then validated using single degree of freedom (SDOF) system with the experiments and blast tests for square slabs and rectangle slabs. Test results showed that the model is accurate in predicting the explosive charge weight and stand-off distance to impose a given damage level on the tested RC slabs especially for close-in blast load. It is shown that the new model is more accurate than the conventional SDOF analysis and is running faster than the FE analysis.
Carbonaceous aerosol AAE inferred from in-situ aerosol measurements at the Gosan ABC super site, and the implications for brown carbon aerosol
C. E. Chung, S.-W. Kim, M. Lee, S.-C. Yoon,S. Lee
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: The Mass Absorption Cross section (MAC) and Absorption ngstr m Exponent (AAE) have been commonly estimated for ambient aerosols but rarely for black carbon (BC) or organic aerosol (OA) alone in the ambient conditions. Here, we provide estimates of BC (and OA) MAC and AAE in East Asian outflow, by analyzing field data collected at the Gosan ABC super site. At this site, EC (and OC) carbon mass, the aerosol absorption coefficient at 7 wavelengths and PM mass density were continuously measured from October 2009 to June 2010. We remove the absorption data with significant dust influence using the mass ratio of PM10 to PM2.5. The remaining data shows an AAE of about 1.27, which we suggest represent the average carbonaceous aerosol (CA) AAE at Gosan. We find a positive correlation between the mass ratio of OC to EC and CA AAE, and successfully increase the correlation by filtering out data associated with weak absorption signal. After the filtering, absorption coefficient is regressed on OC and EC mass densities. BC and OA MACs are found to be 5.1 (3.8–6.1) and 1.4 (0.8–2.0) m2 g 1 at 520 nm respectively. From the estimated BC and OA MAC, we find that OA contributes about 45% to CA absorption at 520 nm. BC AAE is found to be 0.7–1.0, and is probably even lower considering the instrument bias. OA AAE is found to be 1.6–1.8. Compared with a previous estimate of OA MAC and AAE near biomass burning, our estimates at Gosan strongly suggest that the strongly-absorbing so-called brown carbon spheres are either unrelated to biomass burning or absent near the emission source.
The nitrate export in subtropical mountainous catchment: implication for land use change impact
J.-C. Huang,T.-Y. Lee,S.-J. Kao,S.-C. Hsu
Hydrology and Earth System Sciences Discussions , 2010, DOI: 10.5194/hessd-7-9293-2010
Abstract: Agricultural activity is the dominant factor affecting water quality and nitrate export, which causes eutrophication and episodic acidification in downstream water bodies (e.g., reservoirs, lakes, and coastal zones). However, in subtropical mountainous areas such environmental impact due to the land use change was rarely documented. In this study, we investigated 16 sub-catchments during 2007 and 2008 in the Chi-Chia-Wan catchment where is the sole habitat for the endemic species, Formosan landlocked salmon (Oncorhynchus masou formosanus). The results revealed that the NO3-N concentration in pristine catchments varied from 0.144 to 0.151 mg/L without significant seasonal variation. This concentration was comparable with other forestry catchments around the world. However, the annual nitrate export was around 375.3–677.1 kg/km2/yr, much higher than other catchments due to the greater amount of rainfall. This is an important baseline for comparisons with other climate areas. As for the impact of agricultural activities, the catchments with some human disturbance, ~5.2% of the catchment area, might yield 5947.2 kg N/km2/yr – over 10-times higher than that of pristine catchment. Such high export caused by such a low level of disturbance might indicate that subtropical mountainous area is highly sensitive to agricultural activities. As for the land-use effect on nitrate yield, the forestry land might yield 488.5 ± 325.1 kg/km2/yr and the vegetable farm could yield 298 465.4 ± 3347.2 kg/km2/yr – 1000-times greater than the forestry. The estimated nitrate yields for land use classes were a crucial basis and useful for the land manager to assess the possible impacts (e.g., non-point source pollution evaluation and the recovery of land expropriation).
Numerical Computation of Turbulent Flow and Heat Transfer in a Radially Rotating Channel with Wall Conduction
Frank K. T. Lin,G. J. Hwang,S.-C. Wong,C. Y. Soong
International Journal of Rotating Machinery , 2001, DOI: 10.1155/s1023621x01000197
Abstract: This work is concerned with numerical computation of turbulent flow and heat transfer in experimental models of a radially rotating channel used for turbine blade cooling. Reynolds-averaged Navier-Stokes and energy equations with a two-layer turbulence model are employed as the computational model of the flow and temperature fields. The computations are carried out by the software package of “CFX-TASCflow”. Heat loss from the channel walls through heat conduction is considered. Results at various rotational conditions are obtained and compared with the baseline stationary cases. The influences of the channel rotation, through-flow, wall conduction and the channel extension on flow and heat transfer characteristics are explored. Comparisons of the present predictions and available experimental data are also presented.
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