Buoyed by China trade, nationalist-minded politicians launched a foreign policy meant to reduce the role of the U.S. in Latin America. Brazil blocked a U.S. free-trade initiative for the Americas. They teamed with Venezuela to create a regional security council to supplant one that included the U.S. The foreign minister worked from an office with a huge map of the world upside down, offering the message that the era of emerging markets was at hand. But the world wasn’t upside down. While Brazil tied itself more closely to anti-American governments like Venezuela, Argentina and Iran, some regional neighbors—Chile, Colombia and Peru—went around Brazil and cut individual free-trade deals with the U.S.

Anticipating commodity sales, the government spent increasingly heavily. Government banks supplied Brazilians with easy credit. Brazil subsidized energy bills, issued cheap loans to big companies with government ties and built stadiums to host global events such as the 2014 World Cup and the 2016 Olympics.

Meantime, Brazil produced far less oil than predicted. Production actually shrank in some years, as Petróleo Brasileiro SA, PBR 12.80 % known as Petrobras, struggled with the enormous task of developing oil fields in extremely deep water.

Commodities’ support of the economy allowed Brazilian leaders to put off addressing certain problems that had long bedeviled the nation, such as a political system that tended to breed corruption and a bureaucracy that stymied business innovation. “Brazil became complacent because of the intoxicating effects of China trade,”

“Beauty is perfection, to try to perfect yourself more and more every day,” Ms. Mieles said. “That’s how people see it here.” <img src="http://meter-svc.nytimes.com/meter.gif"/>

“You see a woman like this and you say, ‘Wow, I want to look like her,’ ” said Reina Parada, as she sanded a mannequin torso in the workshop. Although she cannot afford it, she said, she would like to get implant surgery someday. “It gives you better self-esteem.”

Cosmetic procedures are so fashionable here that a woman with implants is often casually referred to as “an operated woman.” Women freely talk about their surgeries, and mannequin makers jokingly refer to the creations as being “operated” as well.

The embrace of plastic surgery clashes with the government’s socialist ideology and frequent talk of creating a society free of the taint of commercialism.

the world’s largest estimated petroleum reserves — has long fed a culture of easy money and consumerism here, along with a penchant for the quick fix and instant gratification.

“Venezuela is known for its oil, and it’s known for its beauty,”

Beauty took on a particularly important role in the late 1970s and ’80s when the country’s beauty queens, already a national obsession, were crowned Miss Universe three times.

And the beauty queens’ fame helped fuel a fascination with cosmetic surgery and procedures like breast implants, tummy tucks, nose jobs and injections to firm the buttocks.

For Mr. Sousa, beauty really is skin deep: “I say that inner beauty doesn’t exist. That’s something that unpretty women invented to justify themselves.”

“We have to recognize the gesture of President Barack Obama, a brave gesture and historically necessary, perhaps the most important step of his presidency,” Mr. Maduro said.

Daniel Ortega, the Nicaraguan president and former Sandinista rebel, was chastising Mr. Obama just days ago, saying the United States deserved the top spot in a new list of state sponsors of terrorism. Then, on Wednesday, he saluted the “brave decisions” of the American president.

“We never thought we would see this moment,” said Brazil’s president, Dilma Rousseff, a former Marxist guerrilla who chided the Obama administration last year over the National Security Agency’s surveillance of her and her top aides. She called the deal with Cuba “a moment which marks a change in civilization.”

“It removes an excuse for blaming the United States for things,”

“In the last Summit of the Americas, instead of talking about things we wanted to focus on — exports, counternarcotics — we spent a lot of time talking about U.S.-Cuba policy,” said the official, who was not authorized to speak publicly. “A key factor with any bilateral meeting is, ‘When are you going to change your Cuba policy?’

But while sharp differences persist on many issues, other major Washington policy shifts have recently been applauded in the region, including Mr. Obama’s immigration plan and the resettlement in Uruguay of six detainees from Guantánamo Bay.

“There will be radical and fundamental change,” said Andrés Pastrana, a former president of Colombia. “I think that to a large extent the anti-imperialist discourse that we have had in the region has ended. The Cold War is over.”

A more important issue for many Uruguayans involved the handling of economic policy by the Broad Front, a coalition of left-wing parties, with Uruguay registering average growth of nearly 6 percent a year during the last nine years. Even as growth slowed this year, cautious economic policies were seen as shielding the country from external shocks.

“Practically 70 percent of Uruguayans hold a positive or very positive view of the economic situation in the country,”

during his first term, Dr. Vázquez also governed with his own style, reserving one morning each week to continue practicing medicine.

An increase in violent crime also weighed on voters, and Mr. Lacalle Pou, the conservative challenger and son of a former president, ran on a platform seeking to crack down on crime, reduce inflation and improve Uruguay’s schools.

According to the government’s investigation, the students were arrested by police officers in the town of Iguala, in the southwestern state of Guerrero, and handed over to the local drug gang on the orders of the mayor, José Luis Abarca, on the night of Sept. 26.

Investigators say they believe the students were killed that night and their bodies burned. But the students’ families have refused to believe the government’s version, and daily protests, led by demonstrators bearing pictures of the missing, are a reminder of the government’s failure to improve security and its inability to tackle corruption.

“The real question is whether the Mexican people, who have been promised investigations, overhauls, special commissions, anti-corruption campaigns and institutional reorganizations by this president — and nearly every other authority since the Mexican Revolution — will believe these latest promises,”

“You can’t announce credible strategies to deal with corruption without facing his own scandal of his wife’s white house, whether the conflict of interest is real or not,” said Fernando Dworak, a political analyst and columnist. “He needs to give the message, it starts with himself.”

Analysts said many of the proposals, if not new ideas, were needed, but questioned whether Mr. Peña Nieto had the credibility to pull them off because of scandals under his watch.

Some analysts saw reining in municipal police as a crucial step but questioned whether state forces were any more up to the task, given their own histories of corruption and drug ties.

On Thursday, the decapitated bodies of 11 young people were found in Guerrero State, the same state where the students went to school and disappeared. The governor also said reports of a mass abduction before the one in Iguala would also be investigated.