Inkham C.,Chiang Mai University |
Sueyoshi K.,Niigata University |
Ohtake N.,Niigata University |
Ohyama T.,Niigata University |
Ruamrungsri S.,Institute for Science and Technology
European Journal of Horticultural Science | Year: 2011
We determined the critical nitrogen (N) level in fieldgrown Curcuma alismatifolia Gagnep. by applying N at a rate of 3.75, 7.5, 15, 30, and 60 g N plant-1 as urea. Plant growth and N critical levels were determined 105 d after planting (flowering stage). To establish critical N levels in plant tissue, the relationship between rhizome yield and the N concentrations in the first fully expanded leaf from the bottom of 1st order shoots as investigated. The rate of N application had a significant effect on growth, plant dry weight, leaf N concentrations, and leaf chlorophyll content. Leaf N concentrations were similar for all treatments up to 30 g N plant-1, but increased when N was applied at 60 g N plant-1. Rhizome yields increased with increasing leaf N up to about 1-1.5% N, but were relatively constant at a higher leaf N. The critical leaf N level response to 90% of the maximum yield was 1.51%. Most N concentrations in the various tissues increased with increasing N supply. The method for determining critical N levels provides an accurate description of the relationship between leaf N and rhizome yield and may be used by growers to predict the N requirement of Curcuma plants. Source
Inkham C.,Chiang Mai University |
Sueyoshi K.,Niigata University |
Ohtake N.,Niigata University |
Ohyama T.,Niigata University |
And 2 more authors.
Thai Journal of Agricultural Science | Year: 2011
The effects of different temperatures (30/24°C and 30/18°C day/night temperatures) and N sources; nitrate (NO 3 -), ammonium (NH 4 +), mixed-N source (50 NO 3 -:50 NH 4 +) in the nutrient solution on growth and N assimilation of Curcuma alismatifolia was studied in a soil-less culture medium. Plant grew taller when grown under the 30/24°C treatment and flower quality in terms of stalk length, size of inflorescence and number of bracts declined at low night temperatures. The highest nitrogen concentration (mg plant -1) in leaves was obtained when plants were supplied with NO 3 -as the nitrogen source. Most nitrogen assimilation occurred in leaves at 30/24°C, and in fibrous roots at 30/18°C. There were positive linear relationships between the NO 3 - content and NR activity in leaves, when plants were grown under both 30/24°C (R 2= 0.99) and 30/18°C (R 2= 0.96) treatments. The total amino acid concentration in NH 4 +-fed plants was significantly higher than that of NO 3 --fed plants. Glutamic acid (Glu) was recognized as a major form of accumulated N in old rhizomes, particularly in plants supplied with NO 3 -N at 30/18°C, while asparagine (Asn) and aspartic acid (Asp) were the major form of the accumulated N in fibrous roots when plants were cultivated with low night temperature (30/18°C). Source
Robots could learn a lot from babies, for example, how the latter acquire new movements. Children explore the world through play. In the process, they not only discover their environment but also their own bodies. As Ralf Der of the Max Planck Institute for Mathematics in the Sciences and Georg Martius from the Institute for Science and Technology in Klosterneuburg, Austria have now shown in simulations with robots, that their brains, made of artificial neurons, do not need a higher-level control center for generating curiosity. Curiosity arises solely from feedback loops between sensors that provide stimuli about interactions of the robot’s body with the environment on the one hand and motion commands on the other. The robot’s control unit generates commands for new movements based purely on sensory signals. From initially small, and even passive movements, the robot develops a motor repertoire without specific higher-level instructions. Until now, robots capable of learning have been given specific goals and have then been rewarded when they achieve them. Or researchers try to program curiosity into the robots. “What fires together, wires together”, a rule formulated by Canadian psychologist Donald Hebb, is well known to neuroscientists. This law states that the more often two neurons are active simultaneously, the more likely they link together and form complex networks. Hebb’s law is able to explain the formation of memory but not the development of movements. To learn to crawl, grasp or walk, people and adaptive robots need playful curiosity that prompts them to learn new movements. Ralf Der from the Max Planck Institute for Mathematics in the Sciences and Georg Martius, who until recently researched at the same Max Planck Institute and is now continuing his work at the Institute for Science and Technology in Klosterneuburg, Austria, have now demonstrated, that no higher-level command center is required, which is in contrast to what many researchers believe. “We’ve found that robots, at least, can develop motor skills without the need for a specific program for curiosity, meaning the explicit drive for increasing information in their artificial neural network,” said Georg Martius. Together with Ralf Der, he has formulated a new sensorimotor learning rule, according to which links form in artificial neural networks and possibly also in the brains of babies which allow robots and young children to learn new movements depending on the situation. Neuronal networks form when the body and environment interact The learning rule is based on a model that mimics the dynamic interaction between three components: the body, the brain and the environment, i.e. in robots an artificial neural network. Initially there are no structures in the brain of the robot that control movements. The relevant neural networks form when the body interacts with the environment and the limbs are bent somewhat because they encounter an obstacle. This lies at the root of sensorimotor learning, the robot learns how to move. For the learning process to begin at all, an initial impetus from the outside is required in this model, Martius explains: “First, nothing happens at all. If the system is at rest, the neurons do not receive any signals.“ The researchers therefore triggered a passive sensory stimulus in their robot, for example by leading it around on a virtual thread or simply by letting it sink to the floor so that its trunk, arms or legs are bent. Much as in humans, who after a stroke, for example, initially regain control of their arms or legs by passive movements, passive sensory stimuli in the robotic brain give rise to an initial learning signal. Though this is very weak, the sensorimotor control center uses it to generate a small, but slightly modified motion that generates a new sensory stimulus, which in turn is converted into a movement. Thus, stimuli and motor commands mutually propel each other to generate a coordinated pattern of movements. Feedback between sensor signals and movement produces curiosity The robot then performs the movement pattern until it is disturbed. For example, the robot crawls up to an obstacle. At the obstacle, the robot develops new movement patterns. One of them will eventually allow it to overcome or bypass the obstacle. “In this way our robots exhibit a certain curiosity since they learn more and more movements,” explains Georg Martius. “However, their curiosity arises solely from feedback between sensory stimuli and movement command as their body interacts with the environment.” In computer simulations, the researchers applied their learning rule to simple neural networks of virtual hexapods and humanoid robots that learned to locomote this way. They even were able to cooperate with other robots. For example, after a while two humanoid robots joined forces to turn a wheel in a coordinated manner. Martius emphasizes that their system quickly adapts to new situations that are determined by the environment. This is important because “it would be futile to try all possible movements and combinations. They are infinite in number, and that approach would take far too long.” The model therefore does not use random decisions. On the contrary, a specific sensory stimulus is only translated into a single motor command. The same stimulus therefore always gives rise to the same movement. Hence, the robot’s movements are derived directly from its past actions. “However, small changes in the sensory signals can have a large impact on the development of a movement pattern,” said Georg Martius. Initial tests with a real robot were promising In the long term, the researchers want to combine multiple movement patterns from a large repertoire to allow complex actions. Ralf Der and Georg Martius will first test their learning rules on real robots. Initial experiments with an artificial arm have been promising, as the artificial limb developed some skills of a real arm. The experiments confirm that robots and potentially also the human brain need no high-level curiosity center and no specific goals to develop new movements that can ultimately be used in a practical way. Instead, the required neural networks appear to form solely because neurons that respond to external stimuli in the same way form tighter associations. Ralf Der and Georg Martius have therefore formulated a new rule based on Hebb’s law: “Chaining together what changes together”.
Cimadom A.,University of Vienna |
Ulloa A.,Charles Darwin Foundation |
Meidl P.,Institute for Science and Technology |
Zottl M.,University of Cambridge |
And 6 more authors.
PLoS ONE | Year: 2014
Invasive alien parasites and pathogens are a growing threat to biodiversity worldwide, which can contribute to the extinction of endemic species. On the Galápagos Islands, the invasive parasitic fly Philornis downsi poses a major threat to the endemic avifauna. Here, we investigated the influence of this parasite on the breeding success of two Darwin's finch species, the warbler finch (Certhidea olivacea) and the sympatric small tree finch (Camarhynchus parvulus), on Santa Cruz Island in 2010 and 2012. While the population of the small tree finch appeared to be stable, the warbler finch has experienced a dramatic decline in population size on Santa Cruz Island since 1997. We aimed to identify whether warbler finches are particularly vulnerable during different stages of the breeding cycle. Contrary to our prediction, breeding success was lower in the small tree finch than in the warbler finch. In both species P. downsi had a strong negative impact on breeding success and our data suggest that heavy rain events also lowered the fledging success. On the one hand parents might be less efficient in compensating their chicks' energy loss due to parasitism as they might be less efficient in foraging on days of heavy rain. On the other hand, intense rainfalls might lead to increased humidity and more rapid cooling of the nests. In the case of the warbler finch we found that the control of invasive plant species with herbicides had a significant additive negative impact on the breeding success. It is very likely that the availability of insects (i.e. food abundance) is lower in such controlled areas, as herbicide usage led to the removal of the entire understory. Predation seems to be a minor factor in brood loss. © 2014 Cimadom et al. Source
Driverless electric cars shuttle between energy-saving buildings topped with arrays of solar panels. Traditional Arabic architecture mixes with modern technology, as narrow shaded alleys run between brick-coloured buildings, focusing the wind and keeping temperatures low. On the edge of the complex, a 10-megawatt solar farm lined with photovoltaic panels provides clean energy. First announced in 2007, Masdar city in the suburbs of Abu Dhabi has not yet become the city of 40,000 authorities promised, with only a few hundred people, mainly students, in residence. But the complex—which hosts the International Renewable Energy Association Agency (IRENA) and the Masdar Institute for Science and Technology—is at the forefront of the UAE's efforts to focus on renewables. The company that bears its name has invested huge sums on green energy—an unusual move for a country better known as an oil and gas producer and exporter. Sitting on 5.9 percent of the world's oil reserves and 3.1 percent of its natural gas, the UAE, a federation of seven sheikhdoms, is a key player in the global energy market. The discovery of commercial quantities of oil in the UAE in the late 1950s transformed the area, turning a few pearl-diving towns wedged between the Gulf and the desert into an economic powerhouse. But its rulers know the oil won't last forever, with Abu Dhabi's Crown Prince Sheikh Mohammed bin Zayed al-Nahyan warning earlier this year that the country's last tanker load will be exported in 50 years. "We understood that for us to maintain our leadership in the (energy) sector, we have to get into renewable, and we have done that," Masdar chief executive officer Ahmad Belhoul told AFP. Nawal al-Hosany, head of sustainability at Masdar, said the UAE had an "ambitious" plan for "leveraging its resources from the hydrocarbon industry into this new sector." The UAE says it is expecting to invest $35 billion in non-hydrocarbon energy by 2020, including $20 billion on the Barakah 5.4-gigawatt nuclear power project. Masdar has joined a number of clean energy projects abroad, Hosany said, investing some of the massive reserves the UAE has built up over the years. "The UAE became the only OPEC country that not only exports oil but also exports renewable energy around the world," she said. Masdar is a partner in the 20-megawatt Gemasolar power plant in southern Spain, the world's first solar power station that generates electricity at night. It also has a 20 percent share in the London Array wind power project, which has a capacity to generate 630 megawatts, enough to power nearly half a million homes in Britain. At home, Masdar spent $600 million to build the Shams 1 plant, the world's largest concentrated solar power plant, west of Abu Dhabi, with a capacity to generate 100 megawatts. It also supported the Solar Impulse bid to fly a solar-powered plane around the world in a trip that took off from Abu Dhabi in March but had to be called off in Hawaii due to a battery fault. In total, Masdar says it is participating in projects that will eventually generate 1.5 gigawatts of power. "Over the past five years, the UAE channelled $840 million into renewable energy projects in 25 countries," said Thani al-Zeyoudi, the head of energy and climate change at the UAE foreign ministry. "We look at this from a development perspectives, not just commercial," said Zeyoudi, who is also the UAE's permanent representative to IRENA. Explore further: Gulf states look to the sun for future power