| 1. |
- Ablikim, M., et al.
(author)
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Measurements of (XcJ)-> K+K-K+K- decays
- 2006
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 642:3, s. 197-202
-
Journal article (peer-reviewed)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. |
- Buvall, Lisa, 1976, et al.
(author)
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Phenotype of early cardiomyopathic changes induced by active immunization of rats with a synthetic peptide corresponding to the second extracellular loop of the human beta-adrenergic receptor
- 2006
-
In: Clin Exp Immunol. - : Oxford University Press (OUP). - 0009-9104. ; 143:2, s. 209-15
-
Journal article (peer-reviewed)abstract
- In the failing human heart, due to idiopathic dilated cardiomyopathy, it has been suggested that the beta1-adrenergic receptor (beta1AR) is a potential pathogenic autoantigen. The aim of the present study was to investigate whether immunization of rats with a synthetic peptide corresponding to the second extracellular loop of the beta1AR (beta1AR EC(II)) was able to induce the early stage of cardiomyopathy and also to investigate immunological and receptor functional parameters at a transcriptional level to permit insights into the autoimmune mechanism in cardiomyopathy. Eleven Whistar Fur rats were immunized with a beta1AR EC(II) peptide (H26R) once a month during 12 months and seven control rats were injected with vehicle according to the same procedure used for the immunized group. Cardiac function, beta1AR autoantibodies and their functional effects on cardiomyocytes were analysed. beta1AR receptor signalling, immunological and cardiomyocyte stretch markers were determined on transcriptional level. In H26R immunized rats, beta1AR autoantibodies were shown to be present and functionally active, cardiac functions in terms of fractional shortening were decreased and beta1-adrenergic receptor kinase (GRK2) mRNA were increased compared with the control group. These data have shown that immunization of rats with a putative antigenic peptide was able to induce an early stage phenotype of cardiomyopathy in the form of cardiac dysfunction and up-regulation of GRK2 as the first step in the desensitization process of the beta1AR, implying the pathological importance of the beta1AR autoantibody.
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| 3. |
- Chen, D., et al.
(author)
-
Dual-wavelength single-longitudinal-mode erbium-doped fibre laser based on fibre Bragg grating pair and its application in microwave signal generation
- 2008
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 44:7, s. 459-460
-
Journal article (peer-reviewed)abstract
- A simple dual-wavelength single-longitudinal-mode erbium-doped fibre laser is proposed by incorporating a fibre Bragg grating pair, which is used as a Fabry-Perot filter with two ultra-narrow (similar to 0.12 pm) transmission bands. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength spacing of similar to 0.08 nm is achieved at room temperature. By beating the dual-wavelengths at a photodetector, a microwave signal at 9.616 GHz is demonstrated with a frequency stability better than 1 MHz and a spectral width less that 10 kHz.
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| 4. |
- Chen, Daru R., et al.
(author)
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Wavelength-spacing continuously tunable multi-wavelength SOA-fiber ring laser based on Mach-Zehnder interferometer
- 2008
-
In: Optics and Laser Technology. - : Elsevier BV. - 0030-3992. ; 40:2, s. 278-281
-
Journal article (peer-reviewed)abstract
- A Mach-Zehnder interferometer (MZI) which is used as a wavelength-spacing tunable comb filter in a fiber ring laser is built by employing an optical variable delay line (OVDL). Stable multi-wavelength semiconductor optical amplifier (SOA)-fiber ring laser based on an SOA and the MZI comb filter is achieved. Wavelength spacing can be continuously tuned by adjusting the OVDL and, as an example, multi-wavelength lasing with the wavelength spacing of 0.4, 0.8, or 1.6 nm is demonstrated. The output of the proposed multi-wavelength SOA-fiber ring laser is quite stable at room temperature and the output spectrum can be adjusted by controlling the bias current of the SOA.
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| 5. |
- Chen, Daru, et al.
(author)
-
Single-longitudinal-mode erbium-doped fiber laser based on a fiber Bragg grating Fabry-Perot filter
- 2007
-
In: Laser physics. - 1054-660X .- 1555-6611. ; 17:10, s. 1246-1248
-
Journal article (peer-reviewed)abstract
- A novel single-longitudinal-mode (SLM) erbium-doped fiber laser with a simple linear cavity based on a fiber Bragg grating Fabry-Perot filter (FBG-FPF) and a narrowband (similar to 0.06 nm) FBG is proposed and demonstrated experimentally. Two uniform FBGs form the FBG-FPF, which has two ultranarrow transmission bands with a bandwidth of 0.12 pm and a wavelength spacing of 0.095 nm. By slightly tuning the central wavelength of the narrowband FBG, SLM lasing at 1549.658 or 1549.563 nm (corresponding to the two transmission peaks of the FBG-FPF) is achieved with a laser output power of similar to 4 mW, when the pump power is similar to 75 mW.
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| 6. |
- Chen, Fu
(author)
-
Epstein-Barr virus (EBV) latent membrane protein (LMP) 2A
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- Epstein-Barr virus (EBV) is a ubiquitous human herpes virus which infects more than 90% of individuals in the population and is causally implicated in lymphoid and epithelial malignancies. Virus invades oropharyngeal mucosa and establishes latency in memory B lymphocytes. Of eleven genes expression in latency, EBV latent membrane protein 2A (LMP2A) is important for maintenance of latency in infected B lymphocytes. This study aims to investigate the biological role of LMP2A in the EBV latent infection of B cells and in epithelial cells, with a special reference to tumorigenesis. LMP 2A is expressed both in peripheral B lymphocytes of normal EBV latently infected individuals, and EBV-associated diseases, such as NPC, HL and mononucleosis. Our studies revealed that LMP2A transcripts along with EBNA1 (U-K splicing) expressed in small, resting high density B lymphocytes of healthy EBV carriers, was detected. These data indicate that LMP2A seems to play a physiologic role in maintenance of viral latency (Paper I). LMP2A transcripts were detected in 17 of 24 (70%) NPC tumour biopsies, together with EBNA1 that was detected in all samples driven by Qp, LMP1 and LMP2B are 90% of NPC (paper II). These results suggest that LMP2A is implicated not only in viral latent biology, but also in oncogenic pathology. We investigated the role of LMP2A in three aspects: LMP2A recruits WW domain-containing ubiquitin -protein ligases (III), effect of LMP2A on hTE RT/telome rase activity (IV) and on oncogenic pathology (V). We show that the PPPPY motifs of LMP2A bind multiple WW domains of E3 protein-ubiquitin ligases of the Nedd4 family, including A1P4 and KIAA0439, and form physiological complexes with LMP2A in EBV-positive B cells. Consequently, LMP2A enhances Lyn and Syk ubiquitination in vivo and correlates with destabilization of the Lyn tyrosine kinase, however, we have not observed any effect of LMP2A on Syk stability. Thus, LMP2A may potentiate a normal mechanism by which Nedd4 family E3 enzymes regulate B-cell signalling. In addition, LMP2A itself is also ubiquitinated and degraded through proteasome. Therefore, it is likely that LMP2A utilizes ubiquitin-mediated degradation through the proteasome complex to regulate the strength of its own signal, and to further modulate processes of differentiation, activation or survival of B cells in vivo. Recently, several lines of evidence have suggested that activation of telomerase may be a critical for cell immortalization and transformation, in contrast, it is silent in general due to a stringent repression of hTERT in most human somatic cells. Therefore, our interest has been focused on the potential effect of LMP2A on the expression of hTERT/telomerase activity. We found, although unexpected and paradoxical, that LMP2A expression led to the transcriptional repression of the hTERT gene accompanied by a decreased telomerase activity in epithelial cells. Furthermore, LMP2A, through ITAM motif, was shown to inhibit the hTERT promoter activity in both B cells and epithelial cells. Thus, one possibility is that the LMP2A effect on hTERT is related to its role in suppressing physiologic B-cell activation. (Paper IV). Syk tyrosine kinase plays an instrumental role in the EBV infection of B-lymphocytes. However, In line with several recent reports, we have found that the Syk was expressed in human epithelial cell lines, 5637 (derived from human bladder carcinoma) and TW03 (derived from NPC). LMP2A transfectants in 5637 cells could enhance cell growth and produce tumours in SCID mice. LMP2A, via ITAM motifs, bound to and phosphorylated Syk. This correlated with the capacity of LMP2A to induce cell invasion. LMP2A expression or downregulation of Syk by shRNA Syk resulted in enhance of invasive capacity in both cell types, as a potential tumour suppressor. We show that Syk could directly interact with the ITAM-like motif in integrin a6b4, suggesting a6b4 may be the link between Syk and LMP2A-induced invasive capacity. (paper V). These data suggest that LMP2A may use ubiquitination to regulates its own signal strength and further to influence epithelial cell behaviour such as cell adhesion and motility.
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| 7. |
- Chen, Jie, et al.
(author)
-
Effects of autoantibodies removed by immunoadsorption from patients with dilated cardiomyopathy on neonatal rat cardiomyocytes
- 2006
-
In: The European Journal of Heart Failure. - : Wiley. - 1388-9842. ; 8:5, s. 460-467
-
Journal article (peer-reviewed)abstract
- INTRODUCTION: Immunoadsorption has been shown to improve cardiac performance and reduce mortality in patients with dilated cardiomyopathy. In this study, the underlying mechanism for these beneficial effects was investigated in cultured rat cardiomyocytes. METHODS AND RESULTS: Immunoadsorption was performed in patients with dilated cardiomyopathy (n=7). Antibody-induced complement-dependent cytotoxicity was investigated by colorimetric MTT. Autoantibodies against the beta(1)-adrenoceptor were detected by ELISA and purified. Column eluent from six patients exhibited a cytotoxic effect, three patients were positive for the beta(1)-adrenoceptor autoantibodies. The purified autoantibodies were able to visualize the beta(1)-adrenoceptors by immunocytofluorescence on rat cardiomyocytes, and also displayed partial agonist properties and induced a positive chronotropic effect, which were blocked by the beta(1)-selective antagonist bisoprolol and the peptide corresponding to the beta(1)-adrenoceptor. Column eluent from one patient induced apoptosis in nick end labelling test (8.1+/-1.7% vs. 2.9+/-1.2% in control, p<0.05). CONCLUSION: Autoantibodies removed by immunoadsorption from patients with dilated cardiomyopathy have a pathophysiological role, as shown by the complement-dependent cytotoxicity and chronotropic action on rat cardiomyocytes. This implies that removal of circulating autoantibodies might be part of the underlying mechanism for improved cardiac function.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Fu, J. J., et al.
(author)
-
Ultra-long-distance FBG sensor system based on spectrum-limited Fourier domain modelocking fibre laser with Raman pumps
- 2008
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 44:16, s. 961-963
-
Journal article (peer-reviewed)abstract
- A novel ultra-long-distance (up to 76 km) fibre Bragg grating (FBG) sensor system based on a spectrum-limited Fourier domain modelocking fibre laser is proposed. Raman pumps are employed to form a Raman amplifier to compensate the transmission loss of the long fibre and ensure ultra-long-distance sensing. Strain sensing based on such an ultra-long-distance FBG sensor system is demonstrated with a signal-to-noise ratio over 22 dB and a sensitivity of 1.03 pm/mu epsilon in the wavelength domain or 18.3 ns/mu epsilon in the time domain.
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| 14. |
- Fu, J., et al.
(author)
-
Trends in graded precipitation in China from 1961 to 2000
- 2008
-
In: Advances in atmospheric Sciences. - : Springer Science and Business Media LLC. - 1861-9533 .- 0256-1530. ; 25:2, s. 267-278
-
Journal article (peer-reviewed)abstract
- Daily precipitation rates observed at 576 stations in China from 1961 to 2000 were classified into six grades of intensity, including trace (no amount), slight (<= 1 mm d(-1)), small, large, heavy, and very heavy. The last four grades together constitute the so called effective precipitation (> 1 mm d(-)1). The spatial distribution and temporal trend of the graded precipitation days are examined. A decreasing trend in trace precipitation days is observed for the whole of China, except at several sites in the south of the middle section of the Yangtze River, while a decreasing trend in slight precipitation days only appears in eastern China. The decreasing trend and interannual variability of trace precipitation days is consistent with the warming trend and corresponding temperature variability in China for the same period, indicating a possible role played by increased surface air temperature in cloud formation processes. For the effective precipitation days, a decreasing trend is observed along the Yellow River valley and for the middle reaches of the Yangtze River and Southwest China, while an increasing trend is found for Xinjiang, the eastern Tibetan Plateau, Northeast China and Southeast China. The decreasing trend of effective precipitation days for the middle-lower Yellow River valley and the increasing trend for the lower Yangtze River valley are most likely linked to anomalous monsoon circulation in East China. The most important contributor to the trend in effective precipitation depends upon the region concerned.
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| 15. |
- Fu, Ying, et al.
(author)
-
Design of semiconductor CdSe core ZnS/CdS multishell quantum dots for multiphoton applications
- 2007
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:17, s. 173102-1-173102-3
-
Journal article (peer-reviewed)abstract
- Optical properties of colloidal II-VI semiconductor CdSe cores with ZnS and CdS multishell quantum dots (QDs) have been studied by experimental characterization and theoretical analysis. Due to the large number of energy states densely compacted in both conduction and valence bands of the quantum dots, strong interband and intraband optical couplings are induced by the multiphoton excitation, implicating an efficient fluorescence of such II-VI-based core-multishell CdSe QDs. This fact in combination with the advantage of the size tolerance of II-VI QDs with respect to the narrow fluorescence bandwidth make these systems excellent candidates for applications using fluorescence induced by multiphoton excitation.
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| 16. |
- Gao, S., et al.
(author)
-
Microwave frequency up/downconversion based on dual-wavelength fibre laser
- 2009
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 45:18, s. 932-933
-
Journal article (peer-reviewed)abstract
- A novel method of microwave frequency up/downconversion is proposed for microwave/millimetre-wave-based radio-over-fibre (RoF) systems. The uplink and downlink are both based on dual-wavelength single-longitudinal-mode fibre laser modulation and heterodyning, which provides the possibility to realise bidirectional RoF transmissions.
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| 17. |
- Guo, Xiao-Hua, et al.
(author)
-
Advanced glycation end products induce actin rearrangement and subsequent hyperpermeability of endothelial cells
- 2006
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In: APMIS : acta pathologica, microbiologica, et immunologica Scandinavica. - : Wiley. - 1600-0463 .- 0903-4641. ; 114:12, s. 874-883
-
Journal article (peer-reviewed)abstract
- This study aimed to determine the effects of advanced glycation end products (AGEs) on endothelial cytoskeleton morphology and permeability, and to detect the underlying signaling mechanisms involved in these responses. Cultured endothelial cells (ECs) were exposed to AGE-modified human serum albumin (AGE-HSA), and EC cytoskeletal changes were evaluated by observing fluorescence of F-actin following ligation with labeled antibodies. Endothelial permeability was detected by measuring the flux of TRITC-albumin across the EC monolayers. To explore the signaling pathways behind AGE-induced EC alteration, ECs were treated with either soluble anti-AGE receptor (RAGE) IgG, or the MAPK inhibitors PD98059 and SB203580 before AGE-HSA administration. To further elucidate possible involvement of the ERK and p38 pathways in AGE-induced EC changes, adenovirus-carried recombinant constitutive dominant-negative forms of upstream ERK and p38 kinases, namely MEK1(A) and MKK6b(A), were pre-infected into ECs 24 h prior to AGE-HSA exposure. AGE-HSA induced actin cytoskeleton rearrangement, as well as EC hyperpermeability, in a dose and time-dependent manner. The effects were attenuated in cells pretreated with anti-RAGE IgG, PD98059 or SB203580, respectively. EC pre-infection with MEK1(A) and MKK6b(A) also alleviated the effect of AGEs. Furthermore, adenovirus-mediated administration of activated forms of either MEK1 or MKK6b alone induced rearrangement of F-actin and hyperpermeability. The results indicate that ERK and p38 MAPK play important roles in the mediation of AGE-induced EC barrier dysfunction associated with morphological changes of the F-actin.
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| 18. |
- Haugen, Espen, 1973, et al.
(author)
-
Parallel gene expressions of IL-6 and BNP during cardiac hypertrophy complicated with diastolic dysfunction in spontaneously hypertensive rats.
- 2007
-
In: International journal of cardiology. - : Elsevier BV. - 1874-1754 .- 0167-5273. ; 115:1, s. 24-8
-
Journal article (peer-reviewed)abstract
- There is increasing evidence showing that inflammation is involved in heart failure. However, heart failure may differ greatly due to different aetiologies. The role of inflammation in hypertensive heart failure, particularly in the early stage of cardiac dysfunction, has not been studied completely. This study aims at finding out whether inflammation is involved in the early stage of heart dysfunction due to hypertension. METHODS: Ten spontaneously hypertensive rats (SHR) and ten age-matched Wistar rats were used. Cardiac morphology and function, as well as coronary flow reserve, were examined by echocardiography. mRNAs for cytokines and brain natriuretic peptide were determined by RT-PCR. RESULTS: The results demonstrate cardiac hypertrophy with increased heart/body weight ratio in SHR. Echocardiographic examination has shown that SHR developed diastolic heart dysfunction as determined by tissue Doppler without decrease in systolic function. In heart biopsies, there were increased mRNA levels for interleukin-6 and brain natriuretic peptide whereas decreased mRNA for interleukin-2, beta adrenergic receptor, interferon and NFkb in SHR as compared to WKY group. Coronary flow remained unchanged in both groups. CONCLUSION: SHR developed cardiac hypertrophy complicated with diastolic heart dysfunction with increased expression of brain natriuretic peptide, down-regulation of beta adrenergic receptors and simultaneous up-regulation of IL-6, which indicates active proinflammatory process as, at least partly, underlying mechanism during the early stage when cardiac hypertrophy associated with diastolic dysfunction occurs.
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| 19. |
- Heard-Costa, Nancy L, et al.
(author)
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NRXN3 is a novel locus for waist circumference : a genome-wide association study from the CHARGE Consortium
- 2009
-
In: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 5:6, s. e1000539-
-
Journal article (peer-reviewed)abstract
- Central abdominal fat is a strong risk factor for diabetes and cardiovascular disease. To identify common variants influencing central abdominal fat, we conducted a two-stage genome-wide association analysis for waist circumference (WC). In total, three loci reached genome-wide significance. In stage 1, 31,373 individuals of Caucasian descent from eight cohort studies confirmed the role of FTO and MC4R and identified one novel locus associated with WC in the neurexin 3 gene [NRXN3 (rs10146997, p = 6.4×10−7)]. The association with NRXN3 was confirmed in stage 2 by combining stage 1 results with those from 38,641 participants in the GIANT consortium (p = 0.009 in GIANT only, p = 5.3×10−8 for combined analysis, n = 70,014). Mean WC increase per copy of the G allele was 0.0498 z-score units (0.65 cm). This SNP was also associated with body mass index (BMI) [p = 7.4×10−6, 0.024 z-score units (0.10 kg/m2) per copy of the G allele] and the risk of obesity (odds ratio 1.13, 95% CI 1.07–1.19; p = 3.2×10−5 per copy of the G allele). The NRXN3 gene has been previously implicated in addiction and reward behavior, lending further evidence that common forms of obesity may be a central nervous system-mediated disorder. Our findings establish that common variants in NRXN3 are associated with WC, BMI, and obesity.
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| 20. |
- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
-
In: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
-
Research review (peer-reviewed)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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| 21. |
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| 22. |
- Ou, H., et al.
(author)
-
Microwave-photonic frequency doubling utilising phase modulator and fibre Bragg grating
- 2008
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 44:2, s. 131-133
-
Journal article (peer-reviewed)abstract
- A frequency doubling approach for optical generation of tunable microwave and millimetre-wave signals is proposed and verified experimentally. The experimental setup is based on an optical phase modulator and a simple uniform fibre Bragg grating. The generated signal is of high quality and can be tuned.
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| 23. |
- Wang, Qin, et al.
(author)
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Experimental Decoy-State Quantum Key Distribution with a Sub-Poissionian Heralded Single-Photon Source
- 2008
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100:9, s. 090501-
-
Journal article (peer-reviewed)abstract
- We have experimentally demonstrated a decoy-state quantum key distribution scheme (QKD) with a heralded single-photon source based on parametric down-conversion. We used a one-way Bennett-Brassard 1984 protocol with a four states and one-detector phase-coding scheme, which is immune to recently proposed time-shift attacks, photon-number splitting attacks, and can also be proven to be secure against Trojan horse attacks and any other standard individual or coherent attacks. In principle, the setup can tolerate the highest losses or it can give the highest secure key generation rate under fixed losses compared with other practical schemes. This makes it a quite promising candidate for future quantum key distribution systems.
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| 24. |
- Yang, X.-F., et al.
(author)
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Effects of Shape and Strain Distribution of Quantum Dots on Optical Transition in the Quantum Dot Infrared Photodetectors
- 2008
-
In: Nanoscale Research Letters. - : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 3:12, s. 534-539
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Journal article (peer-reviewed)abstract
- We present a systemic theoretical study of the electronic properties of the quantum dots inserted in quantum dot infrared photodetectors (QDIPs). The strain distribution of three different shaped quantum dots (QDs) with a same ratio of the base to the vertical aspect is calculated by using the short-range valence-force-field (VFF) approach. The calculated results show that the hydrostatic strain epsilon(H) varies little with change of the shape, while the biaxial strain epsilon(B) changes a lot for different shapes of QDs. The recursion method is used to calculate the energy levels of the bound states in QDs. Compared with the strain, the shape plays a key role in the difference of electronic bound energy levels. The numerical results show that the deference of bound energy levels of lenslike InAs QD matches well with the experimental results. Moreover, the pyramid-shaped QD has the greatest difference from the measured experimental data.
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| 25. |
- Yu, LQ, et al.
(author)
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Uncovering multiple molecular targets for caffeine using a drug target validation strategy combining A 2A receptor knockout mice with microarray profiling
- 2009
-
In: Physiological genomics. - : American Physiological Society. - 1531-2267 .- 1094-8341. ; 37:3, s. 199-210
-
Journal article (peer-reviewed)abstract
- Caffeine is the most widely consumed psychoactive substance and has complex pharmacological actions in brain. In this study, we employed a novel drug target validation strategy to uncover the multiple molecular targets of caffeine using combined A2Areceptor (A2AR) knockouts (KO) and microarray profiling. Caffeine (10 mg/kg) elicited a distinct profile of striatal gene expression in WT mice compared with that by A2AR gene deletion or by administering caffeine into A2AR KO mice. Thus, A2ARs are required but not sufficient to elicit the striatal gene expression by caffeine (10 mg/kg). Caffeine (50 mg/kg) induced complex expression patterns with three distinct sets of striatal genes: 1) one subset overlapped with those elicited by genetic deletion of A2ARs; 2) the second subset elicited by caffeine in WT as well as A2AR KO mice; and 3) the third subset elicited by caffeine only in A2AR KO mice. Furthermore, striatal gene sets elicited by the phosphodiesterase (PDE) inhibitor rolipram and the GABAAreceptor antagonist bicucullin, overlapped with the distinct subsets of striatal genes elicited by caffeine (50 mg/kg) administered to A2AR KO mice. Finally, Gene Set Enrichment Analysis reveals that adipocyte differentiation/insulin signaling is highly enriched in the striatal gene sets elicited by both low and high doses of caffeine. The identification of these distinct striatal gene populations and their corresponding multiple molecular targets, including A2AR, non-A2AR (possibly A1Rs and pathways associated with PDE and GABAAR) and their interactions, and the cellular pathways affected by low and high doses of caffeine, provides molecular insights into the acute pharmacological effects of caffeine in the brain.
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| 26. |
- Zeng, Yong, et al.
(author)
-
Complete band gaps in three-dimensional quantum dot photonic crystals
- 2006
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:11, s. 115325-
-
Journal article (peer-reviewed)abstract
- Nonlocal investigations have been performed about exciton-photon couplings in three-dimensional quantum-dot (QD) photonic crystals and a complete photonic band gap has been found in the band structure of a diamond lattice. The width of such a band gap can be broadened by increasing the filling ratio of the QDs (increasing the QD radius or/and decreasing the lattice constant of the photonic crystal). By decomposing the diamond lattice into two interlacing face-centered-cubic (fcc) sublattices, we have found that by significantly modifying the QD radius in one fcc sublattice (the diamond lattice therefore changed to the zinc blende lattice), the band structure of the zinc blende lattice is in principle the sum of two individual fcc sublattices. However, a huge exciton-photon coupling is observed near the band gaps of the two individual fcc sublattices when the radii of the QDs in the two fcc sublattices approach each other, resulting in the complete band gaps of the diamond structure.
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| 27. |
- Zeng, Yong, et al.
(author)
-
Dynamics of the damping oscillator formed by the collective generation of surface polaritons for extraordinary light transmission through subwavelength hole arrays in thin metal films
- 2007
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 76:12
-
Journal article (peer-reviewed)abstract
- Light transmissions through a subwavelength hole array in a thin metal film are characterized by resonance peaks in the transmission spectrum. In this work we study the surface polaritons (SPs) in perforated thin metal films by analyzing the dynamic behavior of the Poynting vectors based on a full-vector finite-difference time-domain approach. It is shown that each resonance peak in the transmission spectrum is caused by a collective generation of SPs in the form of a dynamic damping oscillator which oscillates in space and time. The energy of the incident light is transported between the upper and the lower metal-air surfaces during the spatial oscillations largely through the air holes. This energy transport mechanism prevails even when the metal-film thickness becomes as thin as 100 nm, under which circumstance the wave functions of the SPs, localized separately on the two metal-air surfaces when the metal film is thick, begin to strongly overlap with each other. The lifetimes of the damping oscillators are different for different resonance peaks in the transmission spectrum and remain distinguishable by the order of their temporal development.
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| 28. |
- Zeng, Yong, et al.
(author)
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Effective dielectric constant of two-dimensional photonic crystals in optical bands
- 2006
-
In: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 138:4, s. 205-210
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Journal article (peer-reviewed)abstract
- By using the Fourier expansion method, we have developed an approach to calculate the effective dielectric index of a two-dimensional photonic crystal. The approach is very general: it can take into account various Bravais lattice structure as well as arbitrary spatial variation of the dielectric index. It has been found that near a nondegenerate frequency w(n)(Gamma) at Gamma point, the transverse magnetic (TM) mode is ordinary, as it is independent of the propagation direction, whereas in general the transverse electric (TE) mode depends on the propagation direction, it is extraordinary. Therefore, a two-dimensional photonic crystal can always be described by an effective dielectric index for TM mode near the nondegenerate frequency w(n)(Gamma). However, the TE mode is much more complicated unless the lattice structure is highly symmetric. Moreover, a two-dimensional square photonic crystal has been identified as an effective birefringent crystal having two negative refractive indexes from the perspective of Snell's law.
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| 29. |
- Zeng, Y, et al.
(author)
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Exciton polaritons of nano-spherical-particle photonic crystals in compound lattices
- 2006
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In: European Physical Journal B. - : Springer Science and Business Media LLC. - 1434-6028 .- 1434-6036. ; 49:3, s. 313-318
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Journal article (peer-reviewed)abstract
- Nonlocal investigations are presented for exciton-photon coupling in three-dimensional nano-spherical-particle photonic crystals in compound lattices for a tailored dielectric environment to optimize the optical properties of nano particles. The photonic band structure can be modified by tuning the nano particle size and the distance between two interlacing identical face-centered sub-lattices making up the photonic crystal lattice. A complete photonic band gap with a gap-midgap ratio as large as 40.82% has been found in the wurzite structure under the current investigation.
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| 30. |
- Zeng, Yong, et al.
(author)
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Extended plane-wave-based transfer-matrix approach to simulating dispersive photonic crystals
- 2006
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In: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 139:7, s. 328-333
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Journal article (peer-reviewed)abstract
- It has been difficult to compute the band structures and transmission spectra for photonic crystals (PCs) with dispersive components included in the periodic units. Here we show that by using an extended plane-wave-based transfer-matrix method, we are able to formulate the problem for computing optical properties of dispersive PCs, including magnetic and left-handed PCs. This approach is very general, since it can treat PCs with arbitrary Bravais lattice composed of materials with arbitrary dielectric permittivities and magnetic permeabilities. Combined with the supercell method, this method can further simulate defective PCs such as PC-based waveguides and microcavities.
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| 31. |
- Zeng, Yong, et al.
(author)
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Finite-difference time-domain simulations of exciton-polariton resonances in quantum-dot arrays
- 2008
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In: Optics Express. - 1094-4087. ; 16:7, s. 4507-4519
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Journal article (peer-reviewed)abstract
- The optical properties of nanosize quantum-dot (QD) arrays are found to vary significantly around the exciton resonance frequency of the QDs. In order to simulate the interactions between electromagnetic waves and QD arrays, a general auxiliary-differential-equation, finite-difference time-domain approach is introduced and utilized in this article. Using this numerical method, the exciton-polariton resonances of single-layer and double-layer GaAs QD arrays are studied. The optical properties of a single-layer QD array are found to be characterized by the Mie resonance of its constituent QDs, while a double-layer QD array is characterized by the quasi-dipole formed by two QDs positioned in each of the two layers.
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| 32. |
- Zeng, Yong, et al.
(author)
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Highly efficient generation of entangled photon pair by spontaneous parametric downconversion in defective photonic crystals
- 2007
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In: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 24:6, s. 1365-1368
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Journal article (peer-reviewed)abstract
- We study the process of spontaneous parametric downconversion in a one-dimensional defective quadratic nonlinear photonic crystal. It is shown that the strong confinements of both the pump and signal waves around the defective layer result in a giant enhancement of the entangled photon-pair generation. An enhancement factor as high as 3.4 X 10(6) is obtained in our defective structure based on the dual-localized modes. Furthermore, the linewidth of the downconverted fields is only 0. 1 nm. Such a photonic crystal structure can be applied as a highly efficient source of entangled photon pairs for highly integrated all-optical circuits.
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| 33. |
- Zeng, Yong, et al.
(author)
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Optical properties of two-dimensional negative-phase-velocity-medium photonic crystals
- 2006
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In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 73:6, s. 066625-
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Journal article (peer-reviewed)abstract
- By an extended plane-wave-based transfer-matrix method, the photonic band structure and the corresponding transmission spectrum have been calculated for a two-dimensional photonic crystal composed of negative-phase-velocity-medium (NPVM) cylindrical rods. Dispersionless anticrossing bands in the two-dimensional NPVM periodic structure are generated by the couplings among surface polaritons localized in the NPVM rods. In part of the negative-phase-velocity frequency region, the photonic band structures of the NPVM photonic crystal are characterized by a topographical continuous dispersion relationship accompanied by many anticrossing bands. The effect of the filling fraction of the NPVM rods on the optical properties of photonic crystals has also been studied.
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| 34. |
- Zeng, Yong, et al.
(author)
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Selective excitation of surface-polariton Bloch waves for efficient transmission of light through a subwavelength hole array in a thin metal film
- 2007
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 76:3, s. 035427-
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Journal article (peer-reviewed)abstract
- Electromagnetic (EM) field was found to be able to transmit efficiently through a subwavelength hole array in a metal thin film at specific resonant frequencies. By analyzing the near-field distributions of EM fields in the array system, as well as the corresponding Fourier spectra, we show that the surface-polariton (SP) Bloch waves focus the energy of the incident plane-wave EM field to the vicinity of the hole at resonances (through SP scattering provided by the periodic hole). Furthermore, the wave vectors of the SP waves that contribute to the focusing effect are quantized as functions of the geometric shape of the holes in such a way that the focusing effect of the EM energy into the hole is maximal. The transmission efficiency and bandwidth at resonances are found to partially depend on the number of SP modes which contribute to the focusing effect.
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