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ULTra (Urban Light Transit) is a personal rapid transit system developed by ULTra PRT, (formerly known as Advanced Transport Systems). The first public system using ULTra has been constructed at London's Heathrow Airport, and has now opened to the public. To reduce fabrication costs, the ULTra uses largely off-the-shelf technologies, such as rubber tyres running on an open guideway. This approach has resulted in a system that ULTra believes to be more economical; the company reports that the total cost of the system (vehicles, infrastructure and control systems) is between 3 million and 5 million per kilometre of guideway. In the case of ULTra, the guideway can consist of as little as two parallel rows of concrete barriers, similar to the bumpers found in a parking lot. The vehicle uses these for fine guidance only; it is able to steer itself around curves by following the barriers passively. No "switching" is required on the track either, as the vehicles can make their own turns between routes based on an internal map. Since the vehicles are battery powered, there's no need for electrification along the track. Instead the vehicles recharge when parked at the stations. As a result, the trackway is similar in complexity to a conventional road surface - a light-duty one as the vehicles will not vary in weight to the extent of a tractor-trailer. Even the stations are greatly simplified; in the case of ground-level tracks, the lack of any substantial infrastructure means the vehicles can stop at any kerb. Stations at Heathrow resemble a parking lot with diagonal slots, with a rain shield similar to the awnings at a gas station. The electric-powered vehicles have four seats, can carry 500-kilogram payload, and are designed to travel at 40 kilometres per hour (25 mph) at gradients of up to 20-percent, although the company has suggested limiting operating routes to 10-percent gradients to improve passenger comfort. The vehicles can accommodate wheelchairs, shopping trolleys and other luggage in addition to the passengers. Construction of the guideway was completed in October 2008. The line is largely elevated, but includes a ground level section where the route passes under the approach to the airport's northern runway. Following various trials, including some using airport staff as test passengers, the line opened to public usage in May 2011. At that time it was described as a passenger trials. As of September 2011 it is fully operational and bus service between the business parking lot and Terminal 5 has been discontinued. The developers expect that users will wait an average of around twelve seconds with 95-percent of passengers waiting for less than one minute for their private pod which will travel up to 40 kilometres per hour (25 mph). If the pilot project is successful, BAA have indicated that they will extend the service throughout the airport and to nearby hotels using 400 pods. [READ THE REST OF THIS ARTICLE]



Yellow jacket or yellow-jacket is the common name in North America for predatory wasps of the genera Vespula and Dolichovespula. Members of these genera are known simply as "wasps" in other English-speaking countries. Most of these are black-and-yellow; some are black-and-white (such as the bald-faced hornet, Dolichovespula maculata), while others may have the abdomen background color red instead of black. They can be identified by their distinctive markings, small size (similar to a honey bee), their occurrence only in colonies, and a characteristic, rapid, side to side flight pattern prior to landing. All females are capable of stinging which can cause pain to the person that has been stung. Yellowjackets are important predators of pest insects. Yellowjackets are social hunters living in colonies containing workers, queens, and males. Colonies are annual with only inseminated queens overwintering. Fertilized queens occur in protected places such as hollow logs, in stumps, under bark, in leaf litter, in soil cavities, and human-made structures. Queens emerge during the warm days of late spring or early summer, select a nest site, and build a small paper nest in which eggs are laid. After eggs hatch from the 30 to 50 brood cells, the queen feeds the young larvae for about 18 to 20 days. Larvae pupate, emerging later as small, infertile females called workers. By mid-summer, the first adult workers emerge and assume the tasks of nest expansion, foraging for food, care of the queen and larvae, and colony defense. From this time until her death in the autumn, the queen remains inside the nest laying eggs. The colony then expands rapidly reaching a maximum size of 4,000 and 5,000 workers and a nest of 10,000 and 15,000 cells in late summer. In 1975, the German yellow jacket first appeared in Ohio and has now become the dominant species over the Eastern Yellow Jacket. It is bold and aggressive, and if provoked, it can sting repeatedly and painfully. It will mark aggressors, and will pursue them if provoked. In the Southeastern United States, where southern yellow jacket nests may persist through the winter, colony sizes of this species may reach 100,000 adult wasps. [READ THE REST OF THIS ARTICLE]



Burj Dubai, a supertall skyscraper under construction in Dubai, United Arab Emirates, is the tallest man-made structure ever built, at 818 m. Construction began on 21 September 2004, and the tower is expected to be completed and ready for occupancy on 4 January 2010. The building is part of the 2 km2 (0.8 sq mi) flagship development called "Downtown Burj Dubai" at the "First Interchange" along Sheikh Zayed Road, near Dubai's main business district. The total budget for the Burj Dubai project is about US$4.1 billion, and for the entire new "Downtown Dubai", US$20 billion. Mohamed Ali Alabbar, the CEO of Emaar Properties, speaking at the Council on Tall Buildings and Urban Habitat 8th World Congress, said that the price of office space at Burj Dubai had reached over US$43,000 per m2 and that the Armani Residences, also in Burj Dubai, were selling for over US$37,500 per m2. Though unconfirmed, Burj Dubai has been rumoured to have undergone several planned height increases since its inception. The design architect, Adrian Smith, felt that the uppermost section of the building did not culminate elegantly with the rest of the structure, so he sought and received approval to increase it to the currently planned height. It has been explicitly stated that this change did not include any added floors, which is fitting with Smith's attempts to make the crown more slender. However, the top of the tower has a steel frame structure, unlike the lower portion's reinforced concrete. The developer, Emaar, has stated this steel section may be extended to beat any other tower to the title of tallest. As construction of the tower progressed, it became increasingly difficult to vertically pump the thousands of cubic metres of concrete that were required. The previous record for pumping concrete on any project was set during the extension of the Riva del Garda Hydroelectric Power Plant in Italy in 1994, when concrete was pumped to a height of 532 m. Burj Dubai exceeded this height on 19 August 2007, and as of 8 November 2007 concrete was pumped to a delivery height of 601 m. In Burj Dubai, concrete was pumped to the 156th floor, while the remaining structure was built of lighter steel. Burj Dubai is highly compartmentalised, with refuge floors built every 30 floors, where people can shelter on their long walk down to safety in case of an emergency. The consistency of the concrete used in the project was essential. It was difficult to create a concrete that could withstand both the thousands of tons bearing down on it and Persian Gulf temperatures that can reach 50 C (122 F). To combat this problem, the concrete was not poured during the day. Instead, ice was added to the mixture and it was poured at night when the air is cooler and the humidity is higher. A cooler concrete mixture cures evenly throughout and is therefore less likely to set too quickly and crack. Any significant cracks could have put the entire project in jeopardy. [READ THE REST OF THIS ARTICLE]



In medicine, a lumbar puncture (colloquially known as a spinal tap) is a diagnostic and at times therapeutic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or very rarely as a treatment ("therapeutic lumbar puncture") to relieve increased intracranial pressure. The most common purpose for a lumbar puncture is to collect cerebrospinal fluid in a case of suspected meningitis, since there is no other reliable tool with which meningitis, a life-threatening but highly treatable condition, can be excluded. Young infants commonly require lumbar puncture as a part of the routine workup for fever without a source, as they have a much higher risk of meningitis than older persons and do not reliably show signs of meningeal irritation (meningismus). In any age group, subarachnoid hemorrhage, hydrocephalus, benign intracranial hypertension and many other diagnoses may be supported or excluded with this test. Lumbar punctures may also be done to inject medications into the cerebrospinal fluid ("intrathecally"), particularly for spinal anesthesia or chemotherapy. Lumbar punctures can be unpleasant for some people, due to increased sensitivity when the needle is inserted to collect the cerebrospinal fluid. [READ THE REST OF THIS ARTICLE]



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