(UNICENTRO)

A fotossíntese é importante para a vida na Terra. Nos cloroplastos dos organismos fotossintetizantes, a energia solar é convertida em energia química que, juntamente com água e gás carbônico (CO₂), é utilizada para a síntese de compostos orgânicos (carboidratos). A fotossíntese é o único processo de importância biológica capaz de realizar essa conversão. Todos os organismos, incluindo os produtores, aproveitam a energia armazenada nos carboidratos para impulsionar os processos celulares, liberando CO₂ para a atmosfera e água para a célula por meio da respiração celular. Além disso, grande fração dos recursos energéticos do planeta, produzidos tanto no presente (biomassa) como em tempos remotos (combustível fóssil), é resultante da atividade fotossintética.

As informações sobre obtenção e transformação dos recursos naturais por meio dos processos vitais de fotossíntese e respiração, descritas no texto, permitem concluir que:

Talk about sleepless nights.

Patients taking prescription sleep aids on a regular basis were nearly five times as likely as non-users to die over a period of two and a half years, according to a recent study. Even those prescribed fewer than 20 pills a year were at risk, the researchers found; heavy users also were more likely to develop cancer 

Unsurprisingly, the findings, published online in the journal BMJ, have caused a quite a stir. Americans filled some 60 million prescriptions for sleeping pills last year, up from 47 million in 2006, according to IMS Health, a health care services company. Panicked patients have been calling doctors’ offices seeking reassurance; some others simply quit the pills cold turkey.

 Some experts were quick to point out the study’s shortcomings. The analysis did not prove that sleeping pills cause death, critics noted, only that there may be a correlation between the two. And while the authors suggested the sleeping pills were a factor in the deaths, those who use sleep aids tend as a group to be sicker than those who don’t use them. The deaths may simply be a reflection of poorer health. 

Still, the findings underscore concern about the exploding use of sleeping pills. Experts say that many patients, especially the elderly, should exercise more caution when using sleep medications, including the non-benzodiazepine hypnotics so popular today, like zolpidem (brand name Ambien), eszopiclone (Lunesta) and zaleplon (Sonata).

“If someone comes to me on a sleeping pill, usually my tactic is to try to take them off it,” said Dr. Nancy A. Collop, president of the American Academy of Sleep Medicine and director of the Emory Sleep Center in Atlanta, who was an investigator in a clinical trial of Lunesta five years ago 

The non-benzodiazepine sedative hypnotics, on the market since the late 1980s, are believed to be safer and less likely to be abused than benzodiazepines or barbiturates. But many people take them for years, even though most are approved only for short-term use and generally their safety and effectiveness have not been evaluated beyond several weeks in clinical trials. (One exception is Lunesta, which was tested for up to six months.)

Some data suggest that the medications do not even do what they promise all that well, said Dr. Steven Woloshin, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice.

“The definition of insomnia is that you get less than six and a half hours of sleep, and it takes you 30 minutes or more to fall asleep,” said Dr. Woloshin, who is advocating for new labeling that spells out how well a drug actually works compared with a placebo. “But even when the drugs work better than placebos, and they don’t always, people still don’t fall asleep in less than 30 minutes, and they still don’t sleep much longer than six hours.”

March 12, 2012 / www.nytimes.com

The underlined word “still” in “Still, the findings underscore concern about the exploding use of sleeping pills.” could be replaced, without changing its meaning, by:

(UNESP) Um resistor ôhmico foi ligado a uma fonte de tensão variável, como mostra a figura.

Suponha que a temperatura do resistor não se altere significativamente com a potência dissipada, de modo que sua resistência não varie. Ao se construir o gráfico da potência dissipada pelo resistor em função da diferença de potencial U aplicada a seus terminais, obteve-se a curva representada em:

[...] a finalidade e alvo último de qualquer ciência consiste em ordenar toda a suma matéria de estudo em um sistema de conceitos, cujo conteúdo deveria ser estabelecido e progressivamente aperfeiçoado mediante a observação de regularidades empíricas, a construção de hipóteses e a verificação das mesmas, até que, um dia, daqui nascesse uma ciência “perfeita” e, consequentemente, dedutiva. 

WEBER, Max. Sociologia. São Paulo: Ática, 1991. p. 121. 

O pensamento do autor acerca do desenvolvimento do conhecimento evidencia que a