<P> The pouring process has an influence on a beer's presentation . The rate of flow from the tap or other serving vessel, tilt of the glass, and position of the pour (in the centre or down the side) into the glass all influence the end result, such as the size and longevity of the head, lacing (the pattern left by the head as it moves down the glass as the beer is drunk), and the release of carbonation . A beer tower is a beer dispensing device, usually found in bars and pubs, that consists of a cylinder attached to a beer cooling device at the bottom . Beer is dispensed from the beer tower into a drinking vessel . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2018) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2018) (Learn how and when to remove this template message) </Td> </Tr> <P> Beer contains ethanol, an alcohol, which has short and long - term effects on the user when consumed . Different concentrations of alcohol in the human body have different effects on a person . The effects of alcohol depend on the amount an individual has drunk, the percentage of alcohol in the beer and the timespan over which the consumption took place, the amount of food eaten and whether an individual has taken other prescription, over-the - counter or street drugs, among other factors . Drinking enough to cause a blood alcohol concentration (BAC) of 0.03%--0.12% typically causes an overall improvement in mood and possible euphoria, increased self - confidence and sociability, decreased anxiety, a flushed, red appearance in the face and impaired judgement and fine muscle coordination . A BAC of 0.09% to 0.25% causes lethargy, sedation, balance problems and blurred vision . A BAC from 0.18% to 0.30% causes profound confusion, impaired speech (e.g., slurred speech), staggering, dizziness and vomiting . A BAC from 0.25% to 0.40% causes stupor, unconsciousness, anterograde amnesia, vomiting (death may occur due to inhalation of vomit (pulmonary aspiration) while unconscious) and respiratory depression (potentially life - threatening). A BAC from 0.35% to 0.80% causes a coma (unconsciousness), life - threatening respiratory depression and possibly fatal alcohol poisoning . As with all alcoholic drinks, drinking while driving, operating an aircraft or heavy machinery increases the risk of an accident; many countries have severe criminal penalties against drunk driving . </P>

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