6,971 research outputs found
Structural and Functional Insights into (S)-Ureidoglycine Aminohydrolase, Key Enzyme of Purine Catabolism in Arabidopsis thaliana.
No full textThe ureide pathway has recently been identified as the metabolic route of purine
catabolism in plants and some bacteria. In this pathway, uric acid, which is a
major product of the early stage of purine catabolism, is degraded into
glyoxylate and ammonia via stepwise reactions of seven different enzymes.
Therefore, the pathway has a possible physiological role in mobilization of
purine ring nitrogen for further assimilation. (S)-Ureidoglycine aminohydrolase
enzyme converts (S)-ureidoglycine into (S)-ureidoglycolate and ammonia, providing
the final substrate to the pathway. Here, we report a structural and functional
analysis of this enzyme from Arabidopsis thaliana (AtUGlyAH). The crystal
structure of AtUGlyAH in the ligand-free form shows a monomer structure in the
bicupin fold of the beta-barrel and an octameric functional unit as well as a
Mn(2+) ion binding site. The structure of AtUGlyAH in complex with
(S)-ureidoglycine revealed that the Mn(2+) ion acts as a molecular anchor to bind
(S)-ureidoglycine, and its binding mode dictates the enantioselectivity of the
reaction. Further kinetic analysis characterized the functional roles of the
active site residues, including the Mn(2+) ion binding site and residues in the
vicinity of (S)-ureidoglycine. These analyses provide molecular insights into the
structure of the enzyme and its possible catalytic mechanism.
AD - From the Department of Agricultural Biotechnology and
Faith in Hebrews: Analysis within the Context of Christology, Eschatology, and Ethics
No full textVictor (Sung-Yul) Rhee argues that faith in Hebrews is both Christologically and eschatologically oriented. In response to the assertion that faith in Hebrews is removed from Christ, he contends that the author of Hebrews portrays Jesus as both the model and object of faith. Rhee also maintains that the eschatological outlook in Hebrews is not the Hellenistic concept of visible and invisible reality, but the temporal orientation of present and future. The ethical aspects of faith must be interpreted within the context of Christology and eschatology to have a proper understanding of faith in Hebrews.https://digitalcommons.biola.edu/faculty-books/1524/thumbnail.jp
Syngman Rhee Regime's Change and the US, 1960
No full text미국은 이승만을 대한민국 초대 대통령으로 옹립했지만 미국의 모든 정책결정자들이 처음부터 그를 전폭적으로 지지한 것은 아니었다. 오히려 미국은 한국에서 전쟁이 일어나고 이승만이 1952년 부산정치파동과 1954년의 사사오입개헌 등 두 차례에 걸친 탈법적인 개헌으로 장기 집권을 도모하자 이승만을 제거하려 했다. 이승만을 다른 지도자로 교체 했을 때 과연 그만한 리더십을 발휘할 수 있을까에 대한 확신이 없어 미국은 제거 계획을 실행에 옮기지는 않았지만 국면이 바뀔 때마다 대안을 모색했다. 부산정치파동 때에는 한국의 헌정이 완전히 유린되는 것을 막았으며 휴전협상 중에는 미군 철수로 위협하여 이승만을 제어했다. 그러나 갈수록 독재화하는 이승만 정권을 인정하는 것 외에 미국은 뚜렷한 대안이 없었다. 결국 1950년대 말, 한국 정치가 자유당과 내각 및 경무대의 강경파에 의해 농단되는 것을 지켜본 미국은 이승만의 리더십에 대해 회의하게 되었고 여야의 온건파들을 결합하는 대안 체제를 모색하기에 이르렀다. 1950년대 한국 정부의 자율성 수준은 점차 증가했지만 한국의 주권을 무시하는 이승만 제거 계획과 같은 미국의 물리적 수술 공작은 계속 검토되었으며 결국 1960년 이승만의 퇴임으로 1950년대 말부터 후계체제를 모색해오던 미국의 이승만 제거 계획은 결실을 맺었다.Even though the United States made Syngman Rhee the founding father of Korea's new republic, not all of the US decision makers supported him. In face of the Busan Incident of 1952 and Constitutional Amendment of 1954, the US was shocked by Rhee's unlawful provocations. As a consequence, Americans planned to eliminate the President Rhee to power. As they had no appropriate alternative leadership, their plan became the wastepaper. So there was no option except to support the incumbent president Syngman Rhee in the first half of 1950's. In the late 1950's, as the Rhee government attempted to monopolized Korean Politic, the US' skepticism on his authoritarian leadership was deepened. So Washington explored the contingency and succession plans, which was realized in the vortex of
the April revolution of 1960. This episode leads to a conclusion that although the political autonomy of Rhee adminstration against the US became enhanced, the autonomy in practice was fragile actually
Security analysis of Rhee et al.’s public encryption with keyword search schemes: A review
No full textPublic key encryption with keyword search (PEKS) provides an efficient way to search encrypted files. Recently, Rhee et al. contributed their knowledge to propose several literatures in this research area. In this paper, we first review their three famous schemes and then summarize the security weaknesses of the three schemes. Finally, we discuss the security problems about Rhee et al. like scheme and remain an open problem.</p
Modeling of high speed erosion with a morphological updating routine
No full textErosion is a phenomenon present in several industrial processes. In dredging, the jetting of sand in drag heads erodes the sand bed. In construction of offshore infrastructure such as wind turbines, oil and gas production units, marine pipelines, erosion of material near the foundations can put the stability of structures at stake. Furthermore, rivers or even tsunamis are some of the natural phenomena that can be the cause of erosion. C. van Rhee, 2007 and Bisschop et al., 2015, distinguished two regimes for the erosion of sand dependent on the fluid velocity. On one hand, for low flow velocities, 0.5-1m/s, the erosion process is dependent on the size and the density of the sand grains. On the other, for flow velocities >1.5 m/s, the upper layers of sand are sheared. Densely packed sand has a dilatant behaviour to shearing (see image). This dilatant behaviour leads to a drop of pressure in the interior of the sand-bed, creating a hydraulic gradient and forcing water to flow towards the interior of the sand-bed to fill the voids. The hydraulic gradient caused by the drop in pressure acts against the eroding forces adding resistance to the erosion process. This regime is defined as hindered erosion. The improvements in computing power have led to a spread in the use of numerical modelling for industrial purposes. The aim of this thesis is to develop a numerical solver able to model the behaviour of sand-water mixtures with an emphasis on the erosive process. The numerical model was developed in C++ using the Foam-extend 3.2 framework. The sand is modelled using 2 different approaches. It is modelled as a continuum when in suspension and, through the morphological updating routine when settled in a sand-bed. The fluid motion is modelled by a transient incompressible fluid solver (P.I.S.O) using a collocated arrangement of the unknowns. The momentum exchange between suspended sand grains and the fluid is approached by the Boussinesq approximation of the density. The transport of suspended sand is modelled by an advection-diffusion relation, including the hindered settlement effect. The turbulence model is a standard k-ε model. The erosion process is here modelled using the pick-up flux approach (van Rijn, 1984), with a modified stability criterion (θ_cr). X. Lui, 2008 and N. Jacobsen, 2011, corrected the stability criterion calculated from the sand grain properties (θ_(cr,0)) to include the slope effect (θ_slope). For this work, and following the formulation proposed by van Rhee, 2007, the stability criterion will be corrected to include the resistance due to the dilatant behaviour presented previously in this abstract (θ_vR). θ_cr=θ_(cr,0) (θ_slope+θ_vR ) The solver developed was used in two test cases. First, a settling test, with an initial concentration of sand of c=0.3. For this model, the solver shows a good behavior modeling the settling of sediment, nevertheless, the settling velocity is slightly higher than the one seen in the test. In the high speed erosion test, the velocity above the bed varies from 0-6 m/s. The fitting parameter of this model is the bed roughness; which for this test is 1.05 cm. The bed roughness (ks) was fitted to have the same erosion time. The calculated sand-bed height has values similar to the experimental results. The conservation of sediment presents satisfactory results as the error is lower than 1%, for the settling and the erosion test case. The automatic mesh motion presents certain limitations in this specific application. In the settling case an important shrinking of the mesh will lead to instabilities in the calculations of other fields. In the erosion test, the upper row of cells is greatly deformed sacrificing accuracy near the upper boundary. The mesh deformation should be explored more in depth in further studies.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyOffshore and Dredging Engineerin
Deposition of NiOx thin films with radio frequency magnetron sputtering and their characteristics as a source/drain electrode for the pentacene thin film transistor
No full textNiOx films were deposited with radio frequency (rf) magnetron sputtering at various sputtering powers (25-300 W) and deposition temperatures (room temperature to 200 degrees C) using NiO target and pure O-2 as a sputtering gas. Crystallinity, bonding state (Ni+3 and Ni+2), work function, and the resistivity of the film were measured and the performance of the pentacene thin film transistor (TFT) with the NiOx film as a source/drain (S/D) electrode was evaluated. The film properties such as roughness, work function, crystallinity, and bonding state of Ni and O were similar at each sputtering power, and the NiOx film was deposited at around 150 W and room temperature showed lower resistivity of 1.34x10(4) mu Omega cm, lower surface roughness of 0.206 nm, and higher work function of 5.2 eV. With the increase in the deposition temperature, the ratio of Ni2+ ions to Ni3+ ions in the NiOx film was increased, the work function was decreased and the resistivity was increased. A pentacene TFT with NiOx film deposited at 150 W and room temperature showed a device performance better than that with gold film, with mobility of 0.178 cm(2)/V s, threshold voltage of 0.34 V, and on/off ratio of 5.0x10(5). (C) 2008 American Vacuum Society.open111515sciescopu
Korea`s Exercise of Sovereign Rights over Dokdo and its Marginal Seas
No full textThe 1952 Korean Proclamation of the Rhee Line surrounding the Korean peninsula
with several straight lines was similar to the regime of the EEZ, as it
comprised the water-column and the seabed of the adjacent seas up to the
possible maximum outer-limits. It was soon vehemently criticized by Japan, as it
would drive out incoming Japanese fishermen from the declared seas. Japan also
claimed the ownership of the islet of Dokdo or Takeshima, which was included
in the Rhee Line, asserting that it used to be a Japanese territory before the
1910 annexation. Protracted negotiations over a decade produced the 1965 Japan/
Korea Fisheries Agreement, wherein Korea allowed the Japanese fishermen to
fish in the entire Korean waters beyond 12 mile exclusive zone. As a result, the
Rhee Line was no longer to be applicable to the Japanese fishermen. Dokdo was
left without any 12 mile exclusive zone in the hazy zone of joint fisheries
resources survey outside of the zone of joint fisheries resources preservation.
In the 1999 Japan/Korea Fisheries Agreement, Dokdo was to be located in the
nameless zone of joint management of fisheries, influenced by the provisional
arrangement of a practical nature as provided in Articles 74 of the UN Convention
on the Law of the Sea. There was a vehement criticism over such an
arrangement in Korea, because the rocky islet of Dokdo has not been regarded
as a disputed one by Korea due to the solid evidential facts and the sound legal
bases. South Korea had to accept such an arrangement unwillingly while she
was under IMF management when it needed Japans help during the financial
crisis. It had to persuade the angry Koreans saying that the nameless interme-...이 論文을 위하여 서울大學校 法學發展財團 出捐 法學硏究所 基金의 2008學年度 學術
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Authoritarian Regimes of Rhee Syng-man and Park Chung-hee
No full textThis Bachelor's thesis entitled "Authoritarian Regimes of Rhee Syng-man and Park Chung-hee" aims to provide a comparative study of authoritarian regimes of the first two South Korean presidents, and their respective impact on the political system and society of South Korea. With the help of diachronic comparison methods, the author of this thesis focuses on the reasons behind the leaders' choice of regime, as well as on the overall changes in the form of government in South Korea which took place since the division of the Korean Peninsula until the end of the seventies
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