7dB optical power budget improvements of 11.25Gb/s optical OFDM PON systems using optical filters

Wavelength offset super Gaussian optical filters enable 7dB increases in optical power budget of 11.25Gb/s optical OFDM PON systems using directly modulated DFBs, considerably relax filter bandwidth requirement and improve performance robustness to bandwidth variation. © 2011 Optical Society of America.

First experimental demonstration of low-cost VCSEL-intensity modulated end-to-end real-time optical OFDM signal transmission at 11.25Gb/s over 25km SSMFs

Low-cost, narrow modulation bandwidth, un-cooled VCSELs can be utilized to directly modulate 64-QAM-encoded 11.25Gb/s signals for end-to-end real-time optical OFDM transmission over 25km SSMF IMDD systems with excellent performance robustness. © 2011 Optical Society of America.

First real-time experimental demonstrations of 11.25Gb/s optical OFDMA PONs with adaptive dynamic bandwidth allocation.

End-to-end real-time experimental demonstrations are reported, for the first time, of aggregated 11.25Gb/s over 26.4km standard SMF, optical orthogonal frequency division multiple access (OOFDMA) PONs with adaptive dynamic bandwidth allocation (DBA). The demonstrated intensity-modulation and direct-detection (IMDD) OOFDMA PON system consists of two optical network units (ONUs), each of which employs a DFB-based directly modulated laser (DML) or a VCSEL-based DML for modulating upstream signals. Extensive experimental explorations of dynamic OOFDMA PON system properties are undertaken utilizing identified optimum DML operating conditions. It is shown that, for simultaneously achieving acceptable BERs for all upstream signals, the OOFDMA PON system has a >3dB dynamic ONU launch power variation range, and the BER performance of the system is insusceptible to any upstream symbol offsets slightly smaller than the adopted cyclic prefix. In addition, experimental results also indicate that, in addition to maximizing the aggregated system transmission capacity, adaptive DBA can also effectively reduce imperfections in transmission channel properties without affecting signal bit rates offered to individual ONUs.

Aquatic ecology monitoring, water quality, fish, fish catch, sanitation and disease vectors: monitoring no. 11, 4th – 9th September 2012

This monitoring survey No. 11 undertaken between 4th and 9th September 2012 is the second one to be conducted after completion of construction of Bujagali Hydropower Dam. Two pre-construction baseline surveys in April 2000 and April 2006 were conducted and during construction phase, eight monitoring surveys (September 2007, April 2008, April 2009, October 2009, April 2010, September 2010, April 2011, September 2011) were conducted.

HSF2 mRNA 在热应激和大剂量11酸睾酮诱导恒河猴生精细胞凋亡中的表达变化

为了探讨 HSF2 mRNA 在热应激和超生理剂量睾酮诱导恒河猴生精细胞凋亡中的表达变化, 作者建立了手术诱导单侧隐睾和注射大剂量11酸睾酮(TU)恒河猴动物模型, 应用3′末端标记分析(TUNEL)和原位杂交方法, 检测睾丸细胞的凋亡信号和 HSF2的表达变化. TUNEL 结果显示热应激和超生理剂量睾酮能够诱导生精细胞出现凋亡信号, 它分别于处理后第5天和第30天达到最强, 表明热应激和睾酮干扰精子发生可能是通过生精细胞凋亡的方式来实现的. HSF2 mRNA 水平在生精细胞凋亡早期(凋亡信号达到最强以前)略有降低, 而在凋亡高峰期之后其表达急剧下降. Hsf2基因与作者以前研究的 Hsp70-2基因的表达具有时间上的相关性, 表明 HSF2蛋白可能调控 Hsp70-2基因的表达, 而且 HSF2可能通过多种方式影响精子的发生以及抑制生精细胞的凋亡。

P16蛋白和生精细胞凋亡对热压和11酸睾酮诱导的恒河猴无精子症和少精子症中的作用

探讨了P16蛋白和生精细胞凋亡在热压和11酸睾酮诱导恒河猴无精子症和少精子症中作用间的关系。3^末端标记分析(TUNEL)结果显示热应激和超生理剂量睾酮能够诱导生精细胞出现凋亡信号,它分别于处理后d5和d30达到最强。免疫组化结果显示,热压或TU主要诱导精原细胞和其它生精细胞以及Sertoli细胞P16的表达。P16蛋白的表达在生精细胞凋亡晚期,即隐睾手术d10或注射TUd60后迅速升高并维持高表达,该蛋白在生精细胞凋亡晚期可能通过抑制精原细胞的有丝分裂,扰乱正常的精子发生。

Gene mapping of a new coat mutation in mouse

Gene mapping of a mouse coat mutation has been investigated. First, 100 10-bp random primers were used to amplify DNA, but the mutation could not be located by this method because there were no correlation between the amplified products and coat phenotypes. Second, by using Idh1, Car2, Mup1, Pgb1, Hbb, Es10, Es1, Mod1, Gdc1, Ce2, Es3 as genetic markers, linkage test crosses (two-point test) consisting of intercrossing uncovered BALB/c mice (homozygotes) to CBA/N and C57BL/6 mice with normal hair and backcrossing the heterozygotes of the F1 to the uncovered BALB/c mice were made. It was soon evident that the mutation was linked to Es3 on chromosome 11. Furthermore, three-point test was made by using Es3 and D11Mit8 (a microsatellite DNA) as genetic markers. The result showed that the mutation was linked to Es3 with the percentage recombination of (7.89 +/- 2.19)%, and linked to D11Mit8 with the percentage recombination of (26.38 +/- 3.57)%. The percentage recombination between Es3 and D11Mit8 was (32.90 +/- 3.81)%. The mutation was named Uncovered, with the symbol Uncv. According to the recombinations, the loci order was D11Mit8-26.30 +/- 3.57- Uncv-7.89 +/- 2.19-Es3. From the location on the chromosome, it was concluded that the mutation was a new mutation which affected the skin and hair structure of mouse. The Uncv has entered MGD (Mouse Genome Database).

Characterization of a new bradykinin-potentiating peptide (TmF) from Trimeresurus mucrosquamatus

A novel bradykinin-potentiating peptide (BPP), designated as TmF, has been purified to homogeneity from the venom of Trimeresurus mucrosquamatus by 70% cold methanol extraction, Sephadex G-15 gel filtration and reverse-phase high performance liquid chromatography (RP-HPLC). The amino acid sequence of TmF was determined to be pGlu-Gly-Arg-Pro-Leu-Gly-Pro-Pro-Ile-Pro-Pro (pGlu denotes pyroglutamic acid), which shared high homology with other BPPs. The molecular mass of TmF was 1.1107 kD as determinated by electrospray ionization-mass spectrometry (ESI-MS), which was in accordance with the calculated value of 1.1106 kD. The potentiating "unit" of TmF to bradykinin-induced (BK-induced) contraction on the guinea-pig ileum in vitro was (1.13 +/- 0.3) unit (mg/L), and TmF (5.0 x 10(-4) mg/kg) increased the pressure-lowering-effect of bradykinin (5.0 x 10(-5) mg/kg) with approximate descent value of (14 +/- 2) mmHg. In addition, TmF inhibited the conversion of angiotensin I to angiotensin 11, 2 x 10(-3) mg of TmF caused 50% inhibition (IC50) of angiotensin-converting enzyme (ACE) hydrolyzing activity to bradykinin.

Molecular epidemiology of the heterosexual HIV-1 transmission in Kunming, Yunnan Province of China suggests origin from the local IDU epidemic

Molecular epidemiological investigation was conducted among injecting drug users (IDUs) (n = 11) and heterosexuals (n = 15) in Kunming, Yunnan Province of China. HIV-1 genotypes were determined based on the nucleotide sequences of 2.6-kb gag-RT region. The distribution of genotypes among IDUs was as follows: CRF07_BC (5/11) and CRF08_BC (5/11); subtype B' (1/11). Similarly, a majority of Kunming heterosexuals (14/15) were infected with CRF07_BC (4/15), CRF08_BC (6/15), or subtype B' (4/15), known to predominate among IDUs in China. This contrasts with trends in the coastal regions of China and surrounding southeastern Asian countries, where CRF01_AE predominates among heterosexuals. The heterosexual HIV-1 epidemic in Kunming thus appears to derive from the local IDU epidemic. Of note, subtype B' was the most prevalent strain among heterosexuals before 1997, while CRF07_BC and CRF08_BC became predominant in 2002, indicating a transition of HIV-1 genotype distribution between the early and the more recent samples from Kunming heterosexuals.

A MIMO-OFDM testbed for wireless local area networks

We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally,we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system. £.

Extracellular-matrix tethering regulates stem-cell fate.

To investigate how substrate properties influence stem-cell fate, we cultured single human epidermal stem cells on polydimethylsiloxane (PDMS) and polyacrylamide (PAAm) hydrogel surfaces, 0.1 kPa-2.3 MPa in stiffness, with a covalently attached collagen coating. Cell spreading and differentiation were unaffected by polydimethylsiloxane stiffness. However, cells on polyacrylamide of low elastic modulus (0.5 kPa) could not form stable focal adhesions and differentiated as a result of decreased activation of the extracellular-signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling pathway. The differentiation of human mesenchymal stem cells was also unaffected by PDMS stiffness but regulated by the elastic modulus of PAAm. Dextran penetration measurements indicated that polyacrylamide substrates of low elastic modulus were more porous than stiff substrates, suggesting that the collagen anchoring points would be further apart. We then changed collagen crosslink concentration and used hydrogel-nanoparticle substrates to vary anchoring distance at constant substrate stiffness. Lower collagen anchoring density resulted in increased differentiation. We conclude that stem cells exert a mechanical force on collagen fibres and gauge the feedback to make cell-fate decisions.