7,501 research outputs found
The factors that influence the oral health-related quality of life in 12-year-old children: baseline study of a longitudinal research
published_or_final_versio
Investigating freeway traffic hypercongestion between an on-ramp and its immediate upstream off-ramp
This paper applies the freeway traffic congestion dynamics proposed in Laval and Leclercq [2010. “Continuum Approximation for Congestion Dynamics Along Freeway Corridors.” Transportation Science 44 (1): 87–97] but with a modified distribution scheme of freeway merging flows to investigation of traffic hypercongestion on a freeway between an on-ramp and its immediate upstream off-ramp. The reason to make this modification is that the original merging scheme of this dynamics is found to possibly give undesired full priority to the traffic from the on-ramp and also occasionally make the resulting flow going through the merge greater than the available capacity. Traffic hypercongestion in this paper refers to a state where speed and flow change in the same direction as density varies. A homogeneous freeway segment chosen for this investigation includes an on-ramp and an off-ramp, which may correspond to a freeway passing by a city or town, with an off-ramp lying upstream towards the city and an on-ramp downstream. The entry flow from the upstream approach of the freeway was fixed and constant within the time horizon while both deterministic and random on-ramp inflow rates were used in this investigation. Then the formation and dissipation of traffic hypercongestion is investigated as on-ramp demand and off-ramp departure profiles vary. The first finding of this investigation is that the density in the hypercongestion area behind the merge never reached the jam density. Second, the hypercongested area continued to grow as long as the sum of the demand from the upstream of the freeway and that from the on-ramp was greater than the available capacity at the merge. Third, as long as the rate of flow leaving from the freeway via the off-ramp was not smaller than the entry flow rates from the on-ramp, no hypercongestion had been observed. In addition, in analysing the numerical results, a series of discussions was carried out to build the linkage between the on- and off-ramp flow profiles and the generated and attracted demand of the city plus its adjacent area the two ramps served for; these discussions suggest that the balanced generated and attracted demand of the city plus its adjacent area can reduce or even remove traffic hypercongestion behind the merge on the chosen freeway segment.postprin
Preliminary study on TIMS U-Th dating technique and their application
Thermal ionization mass spectrometry (TIMS) U-Th technique in dating purecarbonate has been established in our laboratory and was used to determine the ages of the Holocene coral samples from the South China Sea and a National Reference Material of uranium-series, GBW04413. The TIMS results of GBW04413 are in good agreement with their reference data determined from α-couning, indication that the ages by TIMS U-Th method are reliable. The TIMS ages of the coral samples older than 5ka have slightly older TIMS U-Th ages than their [14] C ages, which agrees with previous studies [12, 13, 16].尝试了用热电离质谱方法测定南海第四纪珊瑚的U- Th 年龄, 并利用国家铀系年龄标准物质GBW04413 来监测分析结果的合理性。结果显示, GBW04413 的TIMS 年龄与作为推荐值的A记数方法测定结果一致, 反映出其可靠性; 而年龄在1ka 左右的珊瑚样品的TIMS 年龄与14C 年龄一致, >5ka 样品的TIMS 年龄老于14C 年龄, 体现两种方法的系统差别。published_or_final_versio
Loss of APD1 in Yeast Confers Hydroxyurea Sensitivity Suppressed by Yap1p Transcription Factor
Ferredoxins are iron-sulfur proteins that play important roles in electron transport and redox homeostasis. Yeast Apd1p is a novel member of the family of thioredoxin-like ferredoxins. In this study, we characterized the hydroxyurea (HU)-hypersensitive phenotype of apd1Δ cells. HU is an inhibitor of DNA synthesis, a cellular stressor and an anticancer agent. Although the loss of APD1 did not influence cell proliferation or cell cycle progression, it resulted in HU sensitivity. This sensitivity was reverted in the presence of antioxidant N-acetyl-cysteine, implicating a role for intracellular redox. Mutation of the iron-binding motifs in Apd1p abrogated its ability to rescue HU sensitivity in apd1Δ cells. The iron-binding activity of Apd1p was verified by a color assay. By mass spectrometry two irons were found to be incorporated into one Apd1p protein molecule. Surprisingly, ribonucleotide reductase genes were not induced in apd1Δ cells and the HU sensitivity was unaffected when dNTP production was boosted. A suppressor screen was performed and the expression of stress-regulated transcription factor Yap1p was found to effectively rescue the HU sensitivity in apd1Δ cells. Taken together, our work identified Apd1p as a new ferredoxin which serves critical roles in cellular defense against HU.published_or_final_versio
Comparison of Small RNA Profiles of Glycine max and Glycine soja at Early Developmental Stages
published_or_final_versio
Entanglement-free Heisenberg-limited phase estimation
Measurement underpins all quantitative science. A key example is the
measurement of optical phase, used in length metrology and many other
applications. Advances in precision measurement have consistently led to
important scientific discoveries. At the fundamental level, measurement
precision is limited by the number N of quantum resources (such as photons)
that are used. Standard measurement schemes, using each resource independently,
lead to a phase uncertainty that scales as 1/sqrt(N) - known as the standard
quantum limit. However, it has long been conjectured that it should be possible
to achieve a precision limited only by the Heisenberg uncertainty principle,
dramatically improving the scaling to 1/N. It is commonly thought that
achieving this improvement requires the use of exotic quantum entangled states,
such as the NOON state. These states are extremely difficult to generate.
Measurement schemes with counted photons or ions have been performed with N <=
6, but few have surpassed the standard quantum limit and none have shown
Heisenberg-limited scaling. Here we demonstrate experimentally a
Heisenberg-limited phase estimation procedure. We replace entangled input
states with multiple applications of the phase shift on unentangled
single-photon states. We generalize Kitaev's phase estimation algorithm using
adaptive measurement theory to achieve a standard deviation scaling at the
Heisenberg limit. For the largest number of resources used (N = 378), we
estimate an unknown phase with a variance more than 10 dB below the standard
quantum limit; achieving this variance would require more than 4,000 resources
using standard interferometry. Our results represent a drastic reduction in the
complexity of achieving quantum-enhanced measurement precision.Comment: Published in Nature. This is the final versio
Calmodulin in complex with the first IQ motif of myosin-5a functions as an intact calcium sensor
© 2016, National Academy of Sciences. All rights reserved. The motor function of vertebrate myosin-5a is inhibited by its tail in a Ca2+-dependent manner. We previously demonstrated that the calmodulin (CaM) bound to the first isoleucine-glutamine (IQ) motif (IQ1) of myosin-5a is responsible for the Ca2+-dependent regulation of myosin-5a. We have solved the crystal structure of a truncated myosin-5a containing the motor domain and IQ1 (MD-IQ1) complexed with Ca2+-bound CaM (Ca2+-CaM) at 2.5-Å resolution. Compared with the structure of the MD-IQ1 complexed with essential light chain (an equivalent of apo-CaM), MD-IQ1/Ca2+-CaM displays large conformational differences in IQ1/CaM and little difference in the motor domain. In the MD-IQ1/Ca2+-CaM structure, the N-lobe and the C-lobe of Ca2+-CaM adopt an open conformation and grip the C-terminal and the N-terminal portions of the IQ1, respectively. Remarkably, the interlobe linker of CaM in IQ1/Ca2+-CaM is in a position opposite that in IQ1/apo-CaM, suggesting that CaM flip-flops relative to the IQ1 during the Ca2+ transition. We demonstrated that CaM continuously associates with the IQ1 during the Ca2+ transition and that the binding of CaM to IQ1 increases Ca2+ affinity and substantially changes the kinetics of the Ca2+ transition, suggesting that the IQ1/CaM complex functions as an intact Ca2+ sensor responding to distinct calcium signals
Initial/boundary-value problems of tumor growth within a host tissue
This paper concerns multiphase models of tumor growth in interaction with a
surrounding tissue, taking into account also the interplay with diffusible
nutrients feeding the cells. Models specialize in nonlinear systems of possibly
degenerate parabolic equations, which include phenomenological terms related to
specific cell functions. The paper discusses general modeling guidelines for
such terms, as well as for initial and boundary conditions, aiming at both
biological consistency and mathematical robustness of the resulting problems.
Particularly, it addresses some qualitative properties such as a priori
nonnegativity, boundedness, and uniqueness of the solutions. Existence of the
solutions is studied in the one-dimensional time-independent case.Comment: 30 pages, 5 figure
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