Modelling of reduced GB transmission system in PSCAD/EMTDC

Energy and environmental issues are two of the greatest challenges facing the world today. In response to energy needs and environmental concerns, renewable energy technologies are now considered the future technologies of choice. Renewable energy is produced from natural sources that are clean and free; however, it is widely accepted that renewable energy is not a solution without challenges. An example of this can be seen in the UK, where there is much interest amongst generation developers in the construction of new large scale onshore and offshore wind farms, especially in Scotland. The stability of electric power systems is also an important issue. It is important to have full knowledge of the system and to be able to predict the behaviour under different situations is an important objective. As a result, several industrial grade power system simulator tools have been developed in order to estimate the behaviour of the electric power system under certain conditions. This paper presents a reduced Great Britain (GB) system model for stability analysis using PSCAD/EMTDC. The reduced model is based upon a future GB transmission system model and, hence, contains different types and mix of generation, HVDC transmission lines and additional interconnection. The model is based on the reduced DIgSILENT PowerFactory model developed by National Grid

PENGARUH MEDIA FILM ELEKTRONIK TERHADAP KEMAMPUAN KREATIF MATEMATIKA SISWA SEKOLAH DASAR

Pembelajaran anak pada usia sekolah dasar banyak yang kurang menggemari mata pelajaran matematika, mereka menganggap pelajaran matematika itu sulit, dikarenakan proses dan metode yang digunakan hanyalah hubungan satu arah yaitu antara guru ke siswa tanpa adanya timbal balik dari siswa ke guru itu sendiri. Hal tersebut menyebabkan anak menjadi pendengar yang pasif sehingga menghambat proses berfikir kreatif matematis seorang anak untuk menyelesaikan permasalahan yang ada dalam pembelajaran matematika. Salah satu hal yang dapat mendorong anak untuk berfikir kreatif matematis adalah dengan penggunaan media ajar yang tepat, salah satunya dengan menggunakan media film elektronik dalam pembelajaran matematika pokok bahasan bangun ruang. Pembelajaran menggunakan media film elektronik dapat mendorong anak untuk berfikir kreatif matematis dengan adanya gambar-gambar yang dapat memancing imajinasi siswa. Dengan demikian pengguanaan media film elektronik diharapkan dapat memberikan pegaruh positif terhadap kemampuan berfikir kreatif matematis siswa sekolah dasar. Penelitian ini menggunakan desain kuasi eksperimen yang menggunakan dua kelompok sebagai objek penelitian yaitu terbagi menjadi kelas eksperimen dan kelas kontrol. Masing-masing kelompok diberi perlakuan yang berbeda, kelas eksperimen menggunakan media film elektronik dalam proses pembelajaran sedangkan kelas kontrol hanya menggunakan pembelajaran konvensional seperti biasanya. Setelah diberi perlakuan rata-rata nilai yang diperoleh masing-masing kelas dibandingkan untuk mengetahui kemampuan berfikir kreatif matematis siswa. Kelas eksperimen mendapat rata-ratasebesar 74,83 sedangkan kelas kontrol mendapat nilai rata-rata sebesar 41,25. Jika dilihat perbandingannya maka kelas eksperimen memiliki nilai rata-rata lebih besar dari kelas kontrol. Dengan kata lain penggunaan media film elektronik memberikan pengaruh positif terhadap kemampuan berfikir kreatif matematis siswa Sekolah Dasar

The effects of antioxidant, butyl hydroxy anisole and polyphosphate on shelf-life of frozen (-180°C) crayfish (Astacus leptodactylus) of the Caspian Sea

Possible effects of antioxidant Butyl Hydroxy Anisole (BHA) and sodium polyphosphate on the shelf-life of frozen Astacus leptodactylus of the Caspian Sea was studied. Samples of the crayfish were dipped in 0.02 and 0.2% BHA and 0.04 and 0.4% sodium polyphosphate for 30 and 60 minutes. The control samples were packed without immersion in the mixture of BHA and sodium polyphosphate. The Peroxide Value (PV), Total Volatile Nitrogen (TVN), total bacteria count and organoleptic tests were carried out on the samples using a time schedule. The results showed that the minimum increase in PV for the samples which were soaked in a mixture of 0.2% BHA and 0.4% sodium polyphosphate for 1 hour were from 0.59 to 0.88 meq/1000g, as compared to the control samples with an increase in the range 0.59 to 3.53meq/1000 g after four months. The PV Value after four month started to be decrease and reached 1.4 meq/1000 grams after sixth months. The results showed that the minimum increase of TVN for the samples which were soaked in a mixture of 0.2% BHA and 0.4% sodium polyphosphate for I hour were from 12.88 to 17.8 mg/100 grams and for the control samples, the increase was from 12.88 to 19.8 mg/100 grams after sixth month. The results also demonstrated that the minimum increase in Total Bacteria Count of for the samples soaked in a mixture of 0.2% BHA and 0.4% sodium polyphosphate for 1 hour were from 9 x 103 to 2 x 101 per gram and for the control samples, the count was from 9 x 103 to 7 x 102 per gram after sixth months. Kruskal—Wallis, chi-square and Duncan tests were conducted on five samples for each specific shelf-life time. Using the results, we conclude that immersing the samples into a mixture of 0.2% BHA and 0.4% sodium polyphosphate for one hour gives the best results in terms of shelf-life and organoleptic tests

Mechanisms Of Telomere Maintenance In Trypanosoma Brucei

Telomeres are a nucleoprotein structure at the end of the chromosome and are essential for genome integrity and chromosome stability. Telomere lengths are primarily maintained by a telomerase-mediated pathway but can be maintained by a homologous recombination-mediated pathway. However, detailed mechanisms of telomere maintenance are still unclear in many eukaryotes, including an important human pathogen, Trypanosoma brucei. Telomeres can be elongated by telomerase in T. brucei, a causative agent of fatal sleeping sickness in humans and nagana in cattle. T. brucei evades host immune response by regularly switching its major surface antigen, variant surface glycoprotein (VSG), a process known as antigenic variation. The telomere structure and telomere proteins play critical roles in T. brucei pathogenesis. In mammalian, yeast, and plant cells, ssDNA binding proteins with OB-fold domains play important roles in coordinating telomere G- and C-strand syntheses. However, no such protein has been described in T. brucei to be specifically associated with the telomere. We identified POLIE, an A-type DNA polymerase, as a crucial telomere complex component in T. brucei and essential in maintaining telomere integrity in T. brucei. Depletion of POLIE in T. brucei leads to an increased amount of DNA damage at telomere/subtelomere, increased frequency of gene conversion-mediated VSG switching, and an increased amount of the telomeric circles (T-circles), suggesting a potential role of POLIE in suppressing DNA recombination at the telomere and the subtelomere. However, I find that telomeric and subtelomeric DNA recombination is unlikely to be mediated by the increased telomeric R-loop level as the telomeric repeat-containing RNA (TERRA) level is significantly lower in POLIE-depleted cells. The telomere G-rich 3’overhangs are dramatically elongated in POLIE-depleted cells, indicating a potential role of POLIE to coordinate telomere G- and C-strand syntheses and suggesting that the long telomere 3’ overhang can induce more telomeric and subtelomeric recombination. In addition, I find that POLIE inhibits telomerase-dependent telomere G-strand extension, identifying POLIE as the first telomere protein that potentially suppresses telomerase in T. brucei. Moreover, depletion of POLIE greatly increases the amount of telomeric C-circles which can be derived from replication stress in the telomere C-strand. Importantly, the elongated telomere 3’ overhang and elevated telomeric C-circle level phenotypes are independent of the telomerase, which suggests that POLIE may promote the telomere C-strand synthesis. Therefore, we identified that POLIE plays a major role in suppressing telomere recombination, coordinating telomerase-mediated telomere G-strand extension, and telomere C-strand synthesis, and maintaining telomere integrity in T. brucei

Heavy metal flocculation at Pirbazar River, Banadar Anzali, south west Caspian Sea

Heavy metal flocculation process was studied in the year 2002 in order to determine the interaction of water in Pirbazar River with Caspian Sea water. The effects of various salinity concentrations of Caspian Sea water were studied on determined heavy metals including Fe, Zn, Pb, Cu, Cd and Cr level of Pirbazar River using APHA method of extraction and measurement. The results illustrated that the level of heavy metal concentration in Pirbazar River were above standard limits and the extent of flocculation depended on both the salinity level and the heavy metal itself. The maximum flocculation for Cd and Cr were recorded at 7.65ppt, for Zn and Fe at 9.35ppt while for Pb and Cd were at 2.55ppt salinity. The order of flocculation with respect to percentage of original concentrations was found to be Zn > Fe > Cr> Cu > Cd> Pb

EVALUATION OF APPARENT DIGESTIBILITY COEFFICIENTS OF DIFFERENT DIETARY PROTEIN LEVELS WITH AND WITHOUT FISH MEAL FOR LABEO ROHITA

The apparent digestibility coefficients of three protein levels of reference diets (without fish meal) and test diets (with fish meal) were estimated for Labeo rohita. Three test diets (test diet-I, test diet-II and test diet-III) and three reference diets (reference diet-I, reference diet-II and reference diet-III) having 28, 30 and 32% protein levels were prepared. Chromic oxide was used as an internal marker in the experimental diets for the evaluation of digestibility of protein levels. The differences in apparent digestibility for dry matter, crude protein, crude fat and gross energy of reference and test diets were highly significant (P<0.01). The apparent digestibility coefficients (ADCs) of dry matter were 32.10 ± 0.30 and 35.30 ± 0.30% for reference and test diets -III. The ADCs of crude protein and crude fat were 77.92 ± 0.10, 69.23 ± 0.06 and 75.77 ± 0.05, 70.40 ± 0.22% for reference and test diets-III, respectively. The values of ADCs of gross energy were maximum for reference diet-III (52.28 ± 0.25%) and test diet-III (48.65 ± 0.78%). The ADCs of dry matter were 19.80 ± 1.40 and 18.15 ± 0.05% for reference and test diet-I. The ADCs of crude protein and crude fat were 73.93 ± 0.05, 68.43 ± 1.58 and 59.49 ± 1.13, 57.02 ± 2.42% for reference and test diet-I respectively. The ADCs values of gross energy were for reference diet-I (42.43 ± 0.36%) and test diet-I (39.09 ± 1.35%). The better ADCs for dry matter, crude protein, crude fat and gross energy were at 32% protein level

Comparative effects of pure spirulina powder and other diets on larval growth and survival of green tiger shrimp, Peneaus semisulcatus

This experiment was carried out in Bandargah Station in Bushehr province. Peneaus semisulcatus larvae were fed on Spirulina platensis as supplementation microalgae. In order to use Spirulina platensis in this study, we have to produce biomass and dry production of this microalga. Determination of length and survival rate of Peneaus semisulcatus larvae was carried out as the objective of the study. Treatments including Z plus (as a supplementation without spirulina), M.C.F (as an imported enriched spirulina), the powder combination of Spirulina platensis with Z plus and Spirulina platensis as live food were compared to Cheatocerus microalgae as a control. The experiment was carried out from nauplii stage to early post larvae. The results of the experiment indicated that the powder combination of Spirulina platensis with Z plus treatment has the most survival rate (76.5%). The maximum of length (4.3mm) observed in control (Cheatocerus spp.). The maximum mortality was observed in zoa stage in spirulina microalgae treatment, because the spiral filamentous of Spirulina sp. was large

Evaluation of the anxiolytic effect of Nepeta persica Boiss. in mice

The aim of the present study was to evaluate the anxiolytic effects of hydroalcoholic extract (HE) of Nepeta persica Boiss. (Lamiaceae) on the elevated plus-maze (EPM) model of anxiety. The extract of arial parts of the plant was administered intraperitoneally to male NMRI mice, at various doses, 30 min before behavioural evaluation. The HE extract of N. persica at the dose of 50 mg kg−1 significantly increased the percentage of time spent and percentage of arm entries in the open arms of the EPM. This dose of plant extract affected neither animal's locomotor activity nor ketamine-induced sleeping time. The 50 mg kg−1 dose of the plant extract seemed to be the optimal dose in producing the anxiolytic effects, lower or higher doses of the plant produce either sedative or stimulant effects. At 100 mg kg−1, the plant extract increased the locomotor activity. These results suggested that the extract of N. persica at dose of 50 mg kg−1 possess anxiolytic effect with less sedative and hypnotic effects than that of diazepam and causes a non-specific stimulation at 100 mg kg−1