| 1. |
- Ablikim, M., et al.
(författare)
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Measurements of (XcJ)-> K+K-K+K- decays
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 642:3, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Using 14M psi(2S) events taken with the BESII detector, chi(cJ) -> 2(K+K-) decays are studied. For the four-kaon final state, the branching fractions are B(chi(c0,1,2) ->.2(K+K-)) = (3.48 +/- 0.23 +/- 0.47) x 10(-3), (0.70 +/- 0.13 +/- 0.10) x 10(-3), and (2.17 +/- 0.20 +/- 0.31) x 10(-3). For the phi K+K- final state, the branching fractions, which are measured for the first time, are B(chi(c0,1,2) -> phi K+K-) = (1.03 +/- 0.22 +/- 0.15) x 10(-3), (0.46 +/- 0.16 +/- 0.06) x 10(-3), and (1.67 +/- 0.26 +/- 0.24) x 10(-4). For the phi phi final state, B(chi(c0,2) -> phi phi) = (0.94 +/- 0.21 +/- 0.13) x 10(-3) and (1.70 +/- 0.30 +/- 0.25) x 10(-3).
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| 2. |
- Gao, Feng, et al.
(författare)
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Preparation and photoabsorption characterization of BiFeO3 nanowires
- 2006
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 89:10, s. 102506-
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite-type polycrystalline BiFeO3 (BFO) nanowires (similar to 50 nm in diameter and similar to 5 mu m in length) were synthesized using the anodized alumina template technique. An energy band gap of similar to 2.5 eV was determined from the UV-visible diffuse reflectance spectrum, and its photocatalytic ability to produce O-2 was revealed under UV irradiation. Weak ferromagnetism at room temperature and superparamagnetism at low temperature were observed for the BFO nanowires, different from the antiferromagnetic order in bulk BFO, reflecting the significant size effects on the magnetic ordering of BFO. (c) 2006 American Institute of Physics.
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| 3. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 4. |
- Yu, Ling-Zhu, et al.
(författare)
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MEK1/2 regulates microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte meiotic maturation.
- 2007
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Ingår i: Cell cycle (Georgetown, Tex.). - 1551-4005. ; 6:3, s. 330-8
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that MAPK plays pivotal roles in oocyte maturation, but the function of MEK (MAPK kinase) remains unknown. We have studied the expression, subcellular localization and functional roles of MEK during meiotic maturation of mouse oocytes. Firstly, we found that MEK1/2 phoshorylation (p-MEK1/2, indicative of MEK activation) was low in GV (germinal vesicle) stage, increased 2h after GVBD (germinal vesicle breakdown), and reached the maximum at metaphase II. Secondly, we found that P-MEK1/2 was restricted in the GV prior to GVBD. In prometaphase I and metaphase I, P-MEK1/2 was mainly associated with the spindle, especially with the spindle poles. At anaphase I and telophase I, p-MEK1/2 became diffusely distributed in the region between the separating chromosomes, and then became associated with the midbody. The association of p-MEK1/2 with spindle poles was further confirmed by its colocalization with the centrosomal proteins, gamma-tubulin and NuMA. Thirdly, we have investigated the possible functional role of MEK1/2 activation by intravenous administration and intrabursal injection of a specific MEK inhibitor, U0126, and by microinjection of MEK siRNA into oocytes. All these manipulations cause disorganized spindle poles and spindle structure, misaligned chromosomes and larger than normal polar bodies. Our results suggest that MEK1/2 may function as a centrosomal protein and may have roles in microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte maturation.
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| 5. |
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| 6. |
- Chen, Baowei, et al.
(författare)
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Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system
- 2006
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Ingår i: Applied organometallic chemistry. - : John Wiley & Sons. - 0268-2605 .- 1099-0739. ; 20:11, s. 747-753
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Tidskriftsartikel (refereegranskat)abstract
- The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC-HGAFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH(3)(OH)(2)] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium-ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first-order for both As(III) and methyl iodide. First-order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026-0.0123 h(-1). The methylation rate varied largely under different reaction conditions.
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| 7. |
- Chen, Cheng, et al.
(författare)
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A 10-bit 500-MS/s 124-mW subranging folding ADC in 0.13 μm CMOS
- 2007
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Ingår i: Proceedings - IEEE International Symposium on Circuits and Systems. - 0271-4310 .- 2158-1525. ; , s. 1709-1712
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Konferensbidrag (refereegranskat)abstract
- A 10-bit two-step subranging folding analog-to-digital converter (ADC) that converts signal at 500 MSample/s is presented. Using dual-channel preprocessing blocks with distributed sample-and-hold circuits and two-stage amplifiers in which auto-zero calibration technique is employed, the proposed 10-bit ADC has a wide input bandwidth (>250MHz). The ADC consumes 124mW from a 1.2V power supply. The performance is verified by Sepctre simulation in a digital 0.13μm CMOS process. The chip occupies an active area of 0.54mm2. © 2007 IEEE.
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| 8. |
- Chen, Cheng, et al.
(författare)
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A 10-bit pipeline ADC using 40-dB opamps and calibrated customized references
- 2007
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Ingår i: 7th International Conference on ASIC, 2007. ASICON '07. - 9781424411320 ; , s. 249-252
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Konferensbidrag (refereegranskat)abstract
- A 10-bit pipeline A/D converter using low gain (<= 40 dB) operational amplifiers (opamps) is presented. Without. interfering the normal analog-to-digital conversion, a continuous reference refreshing technique is exploited. This technique effectively reduces the gain requirement of opamp while the conversion speed is not compromised, allowing the use of simple cascode CMOS inverters. The compensation of finite gain of the opamp is made by using customized reference voltages that is calibrated periodically. The technique has been confirmed by intensive simulations. As a result of the relaxed opamp gain requirement, significant reduction in power consumption can be achieved.
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| 9. |
- Chen, Cheng, et al.
(författare)
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A low-power 8-bit folding A/D converter with improved accuracy
- 2006
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Ingår i: 2006 8th International Conference on Solid-State and Integrated Circuit Technology. - 1424401607
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Konferensbidrag (refereegranskat)abstract
- In this paper, an accuracy improving method for calibration of mismatch-induced errors in folding A/D converter is presented. With dynamic auto-zero calibration for the folder, the transistor size of folding differential input pairs can be reduced considerably while keeping integral nonlinearity (INL) low. Using this technique, an 8-bit folding A/D converter is designed and simulated in MATLAB. Because of the calibration, conventional preamplifiers and offset averaging network before the folders are removed, saving a large power consumption and chip area. Results are demonstrated, showing the improved accuracy and the good agreement with the theoretical prediction
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| 10. |
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