533 research outputs found

    Effect of photoperiod on the cellular fatty acid composition of three tropical marine microalgae

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    The culture of microalgae in hatcheries is promoted for their high essential fatty acid (EFA) content which favors the successful rearing of aquatic animals. In this study, batch cultures of Chaetoceros calcitrans, Chlorella sp. and Nannochloropsis sp.were acclimated under photoperiods of 24:0h, 12:12h and 8:16h L/D regimes at 20ºC to analyze for cellular fatty acid in the logarithmic growth phase. The various photoperiods resulted in differences of cellular fatty acid content of cultivated microalgae revealing influences and strong interactions between the photoperiods studied. The photoperiod of 12:12h L/D regime is recommended for fast and economic batch culture production of Chaetoceros calcitrans, Chlorella sp. and Nannochloropsis sp. cells rich in EFA

    A comparative study of conventional PID and intelligent Fuzzy-PID FordDC motor speed control

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    The development of a Self Tuning Fuzzy proportional-integral-derivative (PID) controller was done to be compared with the conventional controller that is being used in a direct current (DC) motor. Simulation study is used to overcome the appearance of nonlinearities and uncertainties in the system with the proposed controller for the armature voltage controlled DC motors. Each parameter of the Fuzzy-PID controller is self tuned using 49 fuzzy rules in the fuzzy logic controller. The proportional, integral and derivative (KP,KI,KD) gains of the PID controller is being tuned by the controller. Different types of membership functions are evaluated in the fuzzy control and the best performance will be used in Fuzzy-PID for comparative analysis with the conventional PID.The FIS editor from MATLAB defines the membership function and the rules. Load disturbances from a variety of speed response and the step response are simulated from different scenarios.The Fuzzy PID has resulted to be more robust and it is insensitive to variations in the parameter

    Growth of vertically aligned arrays of carbon nanotubes for high field emission

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    International audienceVertically aligned multi-walled carbon nanotubes have been grown on Ni-coated silicon substrates, by using either direct current diode or triode plasma-enhanced chemical vapor deposition at low temperature (around 620 °C). Acetylene gas has been used as the carbon source while ammonia and hydrogen have been used for etching. However densely packed (∼ 109 cm− 2) CNTs were obtained when the pressure was ∼ 100 Pa. The alignment of nanotubes is a necessary, but not a sufficient condition in order to get an efficient electron emission: the growth of nanotubes should be controlled along regular arrays, in order to minimize the electrostatic interactions between them. So a three dimensional numerical simulation has been developed to calculate the local electric field in the vicinity of the tips for a finite square array of nanotubes and thus to calculate the maximum of the electron emission current density as a function of the spacing between nanotubes. Finally the triode plasma- enhanced process combined with pre-patterned catalyst films (using different lithography techniques) has been chosen in order to grow regular arrays of aligned CNTs with different pitches in the micrometer range. The comparison between the experimental and the simulation data permits to define the most efficient CNT-based electron field emitter

    Oseltamivir- and Amantadine-Resistant Influenza Viruses A (H1N1)

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    Surveillance of amantadine and oseltamivir resistance among influenza viruses was begun in Hong Kong in 2006. In 2008, while both A/Brisbane/59/2007-like and A/Hong Kong/2652/2006-like viruses (H1N1) were cocirculating, we detected amantadine and oseltamivir resistance among A/Hong Kong/2652/2006-like viruses (H1N1), caused by genetic reassortment or spontaneous mutation

    Influenza A H5N1 Detection

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    We developed a sensitive and rapid real-time reverse transcription-polymerase chain reaction (RT-PCR) assay to detect influenza A H5N1 virus in clinical samples. This assay was evaluated with samples from H5N1-infected patients and demonstrated greater sensitivity and faster turnaround time than nested RT-PCR

    Distribution and inter-regional relationship of amyloid-beta plaque deposition in a 5xFAD mouse model of Alzheimer’s disease

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    Alzheimer’s disease (AD) is the most common form of dementia. Although previous studies have selectively investigated the localization of amyloid-beta (Aβ) deposition in certain brain regions, a comprehensive characterization of the rostro-caudal distribution of Aβ plaques in the brain and their inter-regional correlation remain unexplored. Our results demonstrated remarkable working and spatial memory deficits in 9-month-old 5xFAD mice compared to wildtype mice. High Aβ plaque load was detected in the somatosensory cortex, piriform cortex, thalamus, and dorsal/ventral hippocampus; moderate levels of Aβ plaques were observed in the motor cortex, orbital cortex, visual cortex, and retrosplenial dysgranular cortex; and low levels of Aβ plaques were located in the amygdala, and the cerebellum; but no Aβ plaques were found in the hypothalamus, raphe nuclei, vestibular nucleus, and cuneate nucleus. Interestingly, the deposition of Aβ plaques was positively associated with brain inter-regions including the prefrontal cortex, somatosensory cortex, medial amygdala, thalamus, and the hippocampus. In conclusion, this study provides a comprehensive morphological profile of Aβ deposition in the brain and its inter-regional correlation. This suggests an association between Aβ plaque deposition and specific brain regions in AD pathogenesis

    Effects of a portion design plate on food group guideline adherence among hospital staff

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    Food group guideline adherence is vital to prevent obesity and diabetes. Various studies have demonstrated that environmental variables influence food intake behaviour. In the present study we examined the effect of a portion design plate with food group portion guidelines demarcated by coloured lines (ETE Plate™). A two-group quasi-experimental design was used to measure proportions of carbohydrate, vegetable and protein portions and user experience in a hospital staff lounge setting in Singapore. Lunch was served on the portion design plate before 12.15 hours. For comparison, a normal plate (without markings) was used after 12.15 hours. Changes in proportions of food groups from 2 months before the introduction of the design plate were analysed in a stratified sample at baseline (859 subjects, all on normal plates) to 1, 3 and 6 months after (in all 1016 subjects on the design plate, 968 subjects on the control plate). A total of 151 participants were asked about their experiences and opinions. Between-group comparisons were performed using ___t___ tests. Among those served on the portion design plate at 6 months after its introduction, the proportion of vegetables was 4·71 % (P < 0·001) higher and that of carbohydrates 2·83 % (P < 0·001) lower relative to the baseline. No significant change was found for proteins (−1·85 %). Over 6 months, we observed different change patterns between the different food group proportions. While participants were positive about the portion design plate, they did not think it would influence their personal behaviour. A portion design plate might stimulate food group guideline adherence among hospital staff and beyond

    Towards a Model-Independent Analysis of Rare BB Decays

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    Motivated by the experimental accessibility of rare BB decays in the ongoing and planned experiments, we propose to undertake a model-independent analysis of the inclusive decay rates and distributions in the processes \bgamaxs~ and \Bsell ~(B=B±B=B^\pm or Bd0B^0_d). We show how measurements of the decay rates and distributions in these processes would allow us to extract the magnitude and sign of the dominant Wilson coefficients of the magnetic moment operator \mb \bar{s}_L \sigma_{\mu \nu} b_R F^{\mu \nu } and the four-fermion operators (sˉLγμbL)(ˉγμ)(\bar{s}_L \gamma_\mu b_L)(\bar{\ell} \gamma^{\mu} \ell) and (sˉLγμbL)(ˉγμγ5)(\bar{s}_L \gamma_\mu b_L)(\bar{\ell} \gamma^{\mu}\gamma^5 \ell). Non-standard-model effects could thus manifest themselves at low energy in rare BB decays through the Wilson coefficient having values distinctly different from their standard-model counterparts. We illustrate this possibility using the examples of the two-doublet Higgs models and the minimal supersymmetric models. The dilepton invariant mass spectrum and the forward-backward asymmetry of +\ell^+ in the centre-of-mass system of the dilepton pair in the decay \Bsell ~are also worked out for the standard model and some representative solutions for the other two models.Comment: LaTeX, 36 pages, 11 figures appended after \end{document} as uu-encoded and compressed .eps files, uses epsf, CERN-TH.7346/9
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