The search for David Gimelfarb, the missing 28-year-old U.S. doctoral candidate, continued in Costa Rica this week without the help of two U.S. Army Blackhawk helicopters that had arrived last Wednesday.

Both helicopters returned to their base in Honduras on Sunday after having assisted in the search for three days – from Aug. 20 to 22. The helicopters were fitted with infrared sensors, equipment that officials had told the Gimelfarb family would be the best way to find their son.

A news release from the U.S. Embassy in Costa Rica said that the helicopters did everything possible to aid the search of the Costa Rican Red Cross.

“We regret that we could not find Mr. Gimelfarb,” the release noted.

Meanwhile, local search teams are searching Rincón de la Vieja National Park for signs of Gimelfarb, who was last seen entering the park on Aug. 11 (see TT Daily News report).

A total of 24 rescuers traveled by horseback to the north side of the more than 34,000-acre park Tuesday morning but were deterred from searching because of high winds and low visibility.

Red Cross officials said the north side of the mountain has not been searched on foot as thoroughly as the south side.

Friends of the Gimelfarb family held a vigil in the U.S. city of Chicago, Illinois – Gimelfarb's hometown – on Tuesday afternoon to raise awareness about the doctoral students' disappearance.

Participants marched through the city carrying signs and gathered at Daley Plaza, a popular rallying spot for demonstrations in downtown Chicago.

Prized by Costa Ricans as the “Harvard” of Central America, the University of Costa Rica (UCR) jumped nearly 600 spots in the world rankings in terms of online visibility, according to the Spain-based High Council for Scientific Research (CSIC).

Latest numbers put UCR at 386 out of 6,000 universities in the world. In Latin America, the college is behind the University of Chile (227), the University of Buenos Aires, Argentina (291), and the National Autonomous University of Mexico.

The Webometrics Ranking of World Universities, which is one of the largest public research bodies in Spain, bases the rankings on the online visibility of the schools, taking into account the number of external links feeding into their Web site and the number of pages contained in a university's web page.

In 2008, UCR ranked 940 in the world.

“Many things we do on a daily basis contributed to this result,” Henning Jensen, vice dean of research at UCR, said in a statement. “They include the protection and improvement of our identity, which has an impact on quality.”

Other Costa Rican schools that made the ranking include the National University of Costa Rica (1,316), the University for Peace (2,214) and the Inter-American Institute for Human Rights (2,458).

A “plague” of rats has cultivated concerns in the agricultural sectors of northwest Costa Rica, causing the government to declare a state of emergency Monday.

The problem is focused in Guanacaste, the central Pacific and the region north of Puntarenas, according to a statement from the Agriculture and Livestock Ministry. It mostly affects the production of sugarcane, rice and corn, while pineapple farms have also faced damages.

It is not so much a plague as an infestation of Central American “country rats” that eat through the stalk of plants and ruin harvests, said Luis Sánchez with the Agriculture and Livestock Ministry.

“It's a very common species in the Central American region,” Sánchez said. “They attack the base of the plants.”

While the invasion has steadily grown in magnitude for four straight years, this year has been the worst so far, due to the unusually dry conditions which have already left many farmers pulling in smaller yields, Sánchez said. The emergency was declared, he said, so that farmers in affected areas can coordinate with the Plant Health Department in eradicating the rats.

“We already have a control campaign,” which began collecting information on the problem in Nov. 2008, Sánchez said. “We are already working in a number of areas, and we are expanding our work.”

The Plant Health Department is responsible for dealing with the rats. They will use anti-rodent baits, along with the massive use of rodent traps, according to the statement.

Acclaimed U.S. violinist Kevin Lawrence will perform a program featuring U.S. chamber music Sept. 3 at 5 p.m., as part of the National Theater's new Music at Dusk concert series (TT, Aug. 21).

Like the highly successful Theater at Noon program, the new series is the brainchild of theater director Jody Steiger, and is designed to attract the after-work crowd. The one-hour concerts take place in the National Theater's elegant foyer every Thursday at 5 p.m. The price of admission is just ¢ 1,000 ($1.70).

Lawrence's recording of the violin works of U.S. composer Arthur Foote has been featured in the United States on the classical-music program “Performance Today,” formerly produced by NPR, and PBS's “Not For Ourselves Alone.”

Thursday's recital features two works by Foote, “Legend” and “Ballade,” as well as “Homage to Iran ” by Henry Cowell and Ravel's Sonata for Violin and Piano. The Juilliard graduate will be accompanied by Costa Rican pianist Laura Castro.