1000 resultados para biological efficience


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Circadian oscillators provide rhythmic temporal cues for a range of biological processes in plants and animals, enabling anticipation of the day/night cycle and enhancing fitness-associated traits. We have used engineering models to understand the control principles of a plant's response to seasonal variation. We show that the seasonal changes in the timing of circadian outputs require light regulation via feed-forward loops, combining rapid light-signaling pathways with entrained circadian oscillators. Linear time-invariant models of circadian rhythms were computed for 3,503 circadian-regulated genes and for the concentration of cytosolic-free calcium to quantify the magnitude and timing of regulation by circadian oscillators and light-signaling pathways. Bioinformatic and experimental analysis show that rapid light-induced regulation of circadian outputs is associated with seasonal rephasing of the output rhythm. We identify that external coincidence is required for rephasing of multiple output rhythms, and is therefore important in general phase control in addition to specific photoperiod-dependent processes such as flowering and hypocotyl elongation. Our findings uncover a fundamental design principle of circadian regulation, and identify the importance of rapid light-signaling pathways in temporal control.

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Nano-sized TiNi powder with an average size of 50nm was consolidated using spark plasma sintering (SPS) at 800 °C for 5min. A layer of anatase TiO 2 coating was formed on the sintered TiNi by chemical reaction with a hydrogen peroxide (H2O2) solution at 60 °C followed by heat treatment at 400 °C to enhance the bioactivity of the metal surface. Cell culture using osteoblast cells and a biomimetic test in simulated body fluid proved the biocompatibility of the chemically treated SPS TiNi. © IOP Publishing Ltd.

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(54 page document)

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(Document pdf contains 25 pages)

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Bolsa Chica Artificial Reef (BCAR) was constructed in November 1986 with 10,400 tons of concrete rubble and eight concrete and steel barges. Prior to any additional augmentation of BCAR, the u.s. Army Corps of Engineers and the California Coastal Commission required the California Department of Fish and Game (CDFG) to survey the bioloqical communities on and around BCAR. In April 1992, qualitative surveys of the biological communities were conducted on one of the eight modules at BCAR and at a nearby sand-only site. One of the modules, Module D, located in 90 feet of water (MLLW), was surveyed for fish, macroinvertebrates, and turf community organisms (small plants and sessile animals). Twelve species of fish were observed, including kelp bass (Paralabrax clathratus) and barred sand bass (P. nebulifer). Eight macroinvertebrate species were observed, rock scallops (Crassedoma giganteum) being the most abundant. The turf community was comprised of thirteen invertebrate taxa, among which erect ectoprocts (Bugula spp.) were the most numerous. Two species of foliose red algae (Rhodymenia pacifica and Anisocladella pacifica) were also observed. The reef has reached an advanced stage of successional development with fish and invertebrate communities diverse and well established. However, due,.to its depth and the turbidity of surrounding waters, this reef is not likely to ever support a diverse algal community. The diversity and abundance of fish and macroinvertebrates were, as to be expected, much lower in the nearby sand-only site. Only two species of fish and seven macroinvertebrate species were observed. Of these, only the sea pen, Stylatula elongata, was common. Overall, when compared to nearby sand-only habitats, Bolsa Chica Artificial Reef appears to contribute substantially to the local biological productivity. In addition, the concrete rubble used in BCAR' s construction appears to be performing as well as the quarry rock used in all of CDFG's experimental reefs. (Document pdf contains 22 pages)

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A study was conducted on a small pond in southeast Texas to evaluate the potential for using remote sensing technology to assess feeding damage on giant salvinia ( Salvinia molesta Mitchell) by the salvinia weevil ( Cyrtobagous salviniae Calder and Sands). Field spectral measurements showed that moderately damaged and severely damaged plants had lower visible and near-infrared reflectance values than healthy plants. Healthy, moderately damaged, and severely damaged giant salvinia plants could be differentiated in an aerial color-infrared photograph of the study site. Computer analysis of the photograph showed that the three damage level classes could be quantified. (PDF has 5 pages.)

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In August 1999, giant salvinia ( Salvinia molesta Mitchell) was found along the lower Colorado River in irrigation drainages. To investigate the slow spread and apparent control of giant salvinia in this region, the herbivorous fish, tilapia (Oreochromis niloticus Trewavas), was examined as a biological control agent. The study was conducted in a 5,000-L recirculating system. (PDF contains 4 pages.)