Questões de Vestibular

    As we all know, electricity is a fundamental need. On a daily basis, we consume electricity even without us knowing it. Just a simple task such as listening to your music player consumes electricity. Today, most of our electric generators and power plants are fed with fossil fuels such as petroleum and coal. However, due to the exponential increase of power demand, fossil fuel supplies are slowly being depleted. Not only that, but also burning fossil fuels has given off greenhouse gases and other unwanted byproducts. Because of this, the search for alternative energy sources is now a necessity. One of the most promising alternative energy sources today is Wind Powered Generators. So, what is a wind-powered generator? Basically it is the use of wind as a mechanical force needed to power an electric generator. Utilizing wind as an energy source is not exactly a new idea. The ancient Persians were the first to use wind to pump water, cut wood, and grind food and others by building windmills. Even today you can find windmills still being used on some farms. It was the use of wind as an electric source that came into existence much later. The first practical wind powered generators were built in 1970, but yet we rarely see them in widespread use today, why? Let’s look at the advantages and disadvantages of the wind powered generator.

    The main advantage of wind powered generators is that they have, ideally, zero gas emissions – unlike fossil-fueled power generators. Because of the alarming effects of greenhouse gases and global warming, we want our power generators to be as clean and as environmentally friendly as possible. Since there is no burning process in a wind powered generator that produces toxic gases, it is very safe to build one in residential areas. Also, with proper engineering and enough wind, these generators can provide a high rate of wattage that can go as high as the Megawatt range. Another advantage is that it can be implemented using several small turbines connected together. This is a good thing when there is not enough space for huge structures.

     The major disadvantage of wind powered generators is that wind power varies greatly from one place to another and from day to day and season to season. Sometimes wind may be strong enough to supply energy, but that strength cannot be maintained due to changes in weather patterns. Needing strong, constant wind to most effectively power wind generators is one reason they are often built in coastal areas. Another disadvantage is that the structure of most practical wind powered generators is huge and bulky. Commonly, its size is proportional to the wind power it can collect.

    Research in wind power has now intensified because of its innate advantages over other power generators. With this increase in interest in wind energy and alternative energy sources as a whole, our future will become brighter and more and more remote areas will eventually enjoy the benefits of clean electric energy. In an electricity-dependent world, power supplies must provide the required electricity for communities and businesses. Wind powered generators might just be the solution for power shortages.

Disponível em: http://mysolarcellhome.org/articles/pros-and-cons-of-wind-powered-generators. 

LONDON (Reuters) - Drinking alcohol produces a harmful chemical in the body which can lead to permanent genetic damage in the DNA of stem cells, increasing the risk of cancer developing, according to research published on Wednesday.

Working with mice in a laboratory, British scientists used chromosome analysis and DNA sequencing to examine the genetic damage caused by acetaldehyde, a harmful chemical produced when the body processes alcohol.

Their findings offered more detail about how alcohol increases the risk of developing 7 types of cancer, including common forms such as breast and bowel cancer. It also showed how the body seeks to defend against the damage alcohol can do.“Some cancers develop due to DNA damage in stem cells. While some damage occurs by chance, our findings suggest that drinking alcohol can increase the risk of this damage,” said Ketan Patel, a professor at the Medical Research Council Laboratory of Molecular Biology, who co-led the study. The World Health Organization’s International Agency for Research on Cancer classifies alcohol as a Group 1 carcinogen, citing “convincing evidence” it causes cancer in humans.

In Wednesday’s study, published in the journal Nature, Patel’s team gave diluted alcohol to mice and then analyzed the effect on the animals’ DNA. They found that acetaldehyde can break and damage DNA within blood stem cells, permanently altering the DNA sequences within these cells.

This is important, Patel said, because when healthy stem cells become faulty, they can give rise to cancerous cells.

Source: www.reuters.com/article/us-health-cancer-alcohol/how alcohol-damages-stem-celldna-and-increases-cancer-risk-idUSKB1ES1N2