Dynamics and stability of wind turbine generators

Synchronous and induction generators are considered. A comparison is made between wind turbines, steam, and hydro units. The unusual phenomena associated with wind turbines are emphasized. The general control requirements are discussed, as well as various schemes for torsional damping such as speed sensitive stabilizer and blade pitch control. Integration between adjacent wind turbines in a wind farm is also considered

Lake Attitash Management Plan; 2010

Management Plan and Comprehensive Lake Inventory of Lake Attitash in Amesbury/ Merrimac, M

Characterisation of the legume SERK-NIK gene superfamily including splice variants: Implications for development and defence

<p>Abstract</p> <p>Background</p> <p><it>SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE </it>(<it>SERK</it>) genes are part of the regulation of diverse signalling events in plants. Current evidence shows SERK proteins function both in developmental and defence signalling pathways, which occur in response to both peptide and steroid ligands. <it>SERKs </it>are generally present as small gene families in plants, with five <it>SERK </it>genes in Arabidopsis. Knowledge gained primarily through work on Arabidopsis SERKs indicates that these proteins probably interact with a wide range of other receptor kinases and form a fundamental part of many essential signalling pathways. The <it>SERK1 </it>gene of the model legume, <it>Medicago truncatula </it>functions in somatic and zygotic embryogenesis, and during many phases of plant development, including nodule and lateral root formation. However, other <it>SERK </it>genes in <it>M. truncatula </it>and other legumes are largely unidentified and their functions unknown.</p> <p>Results</p> <p>To aid the understanding of signalling pathways in <it>M. truncatula</it>, we have identified and annotated the <it>SERK </it>genes in this species. Using degenerate PCR and database mining, eight more <it>SERK</it>-like genes have been identified and these have been shown to be expressed. The amplification and sequencing of several different PCR products from one of these genes is consistent with the presence of splice variants. Four of the eight additional genes identified are upregulated in cultured leaf tissue grown on embryogenic medium. The sequence information obtained from <it>M. truncatula </it>was used to identify <it>SERK </it>family genes in the recently sequenced soybean (<it>Glycine max</it>) genome.</p> <p>Conclusions</p> <p>A total of nine <it>SERK </it>or <it>SERK-like </it>genes have been identified in <it>M. truncatula </it>and potentially 17 in soybean. Five <it>M. truncatula SERK </it>genes arose from duplication events not evident in soybean and Lotus. The presence of splice variants has not been previously reported in a <it>SERK </it>gene. Upregulation of four newly identified <it>SERK </it>genes (in addition to the previously described <it>MtSERK1</it>) in embryogenic tissue cultures suggests these genes also play a role in the process of somatic embryogenesis. The phylogenetic relationship of members of the <it>SERK </it>gene family to closely related genes, and to development and defence function is discussed.</p

An Aid to Students

n/

CCD photometry of 2060 Chiron, 1991 January

Observations of 2060 Chiron was performed on 7 to 8 Jan. 1991 with the Mt. Palomar 1.52 m telescope in the Gunn-R passband. On-chip field stars were used to perform differential reductions. The repeatability of the 5.9 hour light curve was excellent, both within a night and from night to night. No evidence for short-term secular variations similar to those seen last year by both Luu and Jewitt (1990) and Buratti and Dunbar (1991) is seen in the new light curve. Chiron's rotational light curve appears strikingly similar to that obtained a year earlier by Luu and Jewitt (1990), both in amplitude and shape. Both light curves show strongly correlated changes over a timescale of perhaps 15 minutes. These same features were marginally visible in the 1986 light curve. Such behavior is believed to be evidence that Chiron may be more aspherical than the 4 percent intensity variation might otherwise indicate, and favors a viewing geometry where the subearth latitude is rather low. Chiron was much fainter in 1985, when a partial light curve was obtained by Marcialis. Due to the lower sampling rate of these early data, no conclusions can be made regarding the high-frequency light curve structure back then. All three of these light curves differ significantly from that obtained by Buratti and Dunbar (1991), one week before the observations of Luu and Jewitt. The Chiron field was calibrated using Landolt standards on Ut 15 Mar. 1991. A mean R-magnitude of 15.6 + or - 0.1 was found. Variability of 2060 Chiron was demonstrated over timescales of minutes, hours, and years. An intense campaign was urged to monitor the photometric behavior of Chiron throughout the 1990s

Plasma Physics

Contains reports on two research projects.U. S. Atomic Energy Commission under Contract AT(30-1)-184

The 2HA line of Medicago truncatula has characteristics of an epigenetic mutant that is weakly ethylene insensitive

BACKGROUND The Medicago truncatula 2HA seed line is highly embryogenic while the parental line Jemalong rarely produces embryos. The 2HA line was developed from one of the rare Jemalong regenerates and this method for obtaining a highly regenerable genotype in M. truncatula is readily reproducible suggesting an epigenetic mechanism. Microarray transcriptomic analysis showed down regulation of an ETHYLENE INSENSITIVE 3-like gene in 2HA callus which provided an approach to investigating epigenetic regulation of genes related to ethylene signalling and the 2HA phenotype. Ethylene is involved in many developmental processes including somatic embryogenesis (SE) and is associated with stress responses. RESULTS Microarray transcriptomic analysis showed a significant number of up-regulated transcripts in 2HA tissue culture, including nodule and embryo specific genes and transposon-like genes, while only a few genes were down-regulated, including an EIN3-like gene we called MtEIL1. This reduced expression was associated with ethylene insensitivity of 2HA plants that was further investigated. The weak ethylene insensitivity affected root and nodule development. Sequencing of MtEIL1 found no difference between 2HA and wild-type plants. DNA methylation analysis of MtEIL1 revealed significant difference between 2HA and wild-type plants. Tiling arrays demonstrated an elevated level of miRNA in 2HA plants that hybridised to the antisense strand of the MtEIL1 gene. AFLP-like methylation profiling revealed more differences in DNA methylation between 2HA and wild-type. Segregation analysis demonstrated the recessive nature of the eil1 phenotype and the dominant nature of the SE trait. CONCLUSIONS We have demonstrated that EIL1 of Medicago truncatula (MtEIL1) is epigenetically silenced in the 2HA seed line. The possible cause is an elevated level of miRNA that targets its 3'UTR and is also associated with DNA methylation of MtEIL1. Down regulation of MtEIL1 makes it possible to form nodules in the presence of ethylene and affects root growth under normal conditions. Segregation analysis showed no association between MtEIL1 expression and SE in culture but the role and mechanism of ethylene signalling in the process of plant regeneration through SE requires further investigation. The work also suggests that epigenetic changes to a particular gene induced in culture can be fixed in regenerated plants.This work was funded by the Australian Research Council (CEO348212) through the ARC Centre of Excellence for Integrative Legume Research (CILR)

Pengaruh Kualitas Ransum Dna Temperatur Lingkungan

Penelitian untuk mengetahui pengaruh ransum dan suhu lingkungan terhadap karakteristik karkas dan daging telah dilakukan dengan menggunakan 16 ekor domba persilangan Border Leicester x Merino jantan kastrasi, umur 7 bulan, bobot 33.0+1.49 kg. Domba-bomba tersebut dialokasikan secara acak pada perlakuan dalam rancangan acak kelompok dengan struktur faktorial 2 x 2. Perlakuan yang diterapkan adalah suhu lingkungan (20° and 30°C) dan ransum (RPTS: rendah protein tinggi serat, dan TPRS: tinggi protein rendah serat). Ransum TPRS memberikan hasil persentase karkas dan ketebalan lemak punggung yang lebih tinggi daripada ransum RPTS (49.7 vs 44.4 % dan 14.2 vs 6.8 mm berturutan), tetapi tidak terdapat pengaruh nyata suhu terhadap karakteristik karkas. Terdapat interaksi nyata antara suhu dan ransum pada otot mata rusuk. Pada domba yang mendapat ransum RPTS, suhu berpengaruh nyata, sementara pada domba yang mendapat TPRS, suhu tidak berpengaruh nyata. Daging domba yang diberi RPTS mempunyai rasa yang lebih enak daripada domba yang dib,_.i TPRS. Suhu tidak berpengaruh nyata terhadap aroma daging. Baik suhu maupun ransum tidak berpengaruh nyata pada pH, warna maupun keempukan daging. (Kata kunci: Domba jantan kastrasi, Cekaman panas, Karkas, Daging)

HIV-1 Evolutionary Patterns Associated with Metastatic Kaposi's Sarcoma during AIDS.

Kaposi's sarcoma (KS) in HIV-infected individuals can have a wide range of clinical outcomes, from indolent skin tumors to a life-threatening visceral cancer. KS tumors contain endothelial-related cells and inflammatory cells that may be HIV-infected. In this study we tested if HIV evolutionary patterns distinguish KS tumor relatedness and progression. Multisite autopsies from participants who died from HIV-AIDS with KS prior to the availability of antiretroviral therapy were identified at the AIDS and Cancer Specimen Resource (ACSR). Two patients (KS1 and KS2) died predominantly from non-KS-associated disease and KS3 died due to aggressive and metastatic KS within one month of diagnosis. Skin and visceral tumor and nontumor autopsy tissues were obtained (n = 12). Single genome sequencing was used to amplify HIV RNA and DNA, which was present in all tumors. Independent HIV tumor clades in phylogenies differentiated KS1 and KS2 from KS3, whose sequences were interrelated by both phylogeny and selection. HIV compartmentalization was confirmed in KS1 and KS2 tumors; however, in KS3, no compartmentalization was observed among sampled tissues. While the sample size is small, the HIV evolutionary patterns observed in all patients suggest an interplay between tumor cells and HIV-infected cells which provides a selective advantage and could promote KS progression