Posts about Brazil

A single spot in the Sahara that provides huge amounts of nutrients to the Amazon

The Bodélé depression: a single spot in the Sahara that provides most of the mineral dust to the Amazon forest

About 40 million tons of dust are transported annually from the Sahara to the Amazon basin. Saharan dust has been proposed to be the main mineral source that fertilizes the Amazon basin, generating a dependence of the health and productivity of the rain forest on dust supply from the Sahara. Here we show that about half of the annual dust supply to the Amazon basin is emitted from a single source: the Bodélé depression located northeast of Lake Chad, approximately 0.5% of the size of the Amazon or 0.2% of the Sahara. Placed in a narrow path between two mountain chains that direct and accelerate the surface winds over the depression, the Bodélé emits dust on 40% of the winter days, averaging more than 0.7 million tons of dust per day.

Even understanding how connected the global ecosystem is, research like this provides amazing reminders of those connections.

Related: The Amazon Rainforest Would Not Be Without Saharan Dust (podcast interview)Ancient Whale Uncovered in Egyptian DesertNigersaurusThe Sahara Wasn’t Always a DesertElusive Saharan cheetah and Sandcat

Dolphins Saved by People

Is this a bit like man bites dog? In any case it is a happy event. I wish I could have helped.

Related: Florida Dolphin Develop Unique Strategy for Hunting FishDolphin Rescues Beached WhalesFriday Fun: Dolphins Play with Air Bubble RingsDolphin Delivers Deviously for Rewards

Top Countries for Science and Math Education: Finland, Hong Kong and Korea

The 2009 Programme for International Student Assessment (PISA)* report has been released. The report examines the science of 15 year olds from 57 countries in math, science and reading. The main focus of PISA 2009 was reading. The survey also updated performance assessments in mathematics and science.

The Asian countries continue to do very well for several reason including tutoring; they have even turned tutors into rock stars earning millions of dollars. The results show the value of tutors at takelessons.com and such sites to student achievement.

The emphasis is on mastering processes, understanding concepts and functioning in various contexts within each assessment area. the PISA 2012 survey will return to mathematics as the major assessment area, PISA 2015 will focus on science.

Results for the Science portion (rank – country – mean score)(I am not listing all countries):

  • 1 – Finland – 554
  • 2 – Hong Kong – 549
  • 3 – Japan – 539
  • 4 – Korea – 538
  • 5 – New Zealand – 532
  • 6 – Canada – 529
  • 7 – Estonia – 528
  • 8 – Australia – 527
  • 9 – Netherlands – 522
  • 10 – Taiwan – 520
  • 11 – Germany – 520
  • 14 – United Kingdom – 514
  • 21 – USA – 502 (up from 489 and 29th place in 2006)
  • OECD average – 501
  • 25 – France – 498
  • 46 – Mexico – 416
  • 49 – Brazil – 405

Results for the math portion (rank – country – mean score)(I am not listing all countries):
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Capuchin Monkeys Using Stone Tools

This BBC documentary “Clever Monkeys”, narrated by David Attenborough, shows Capuchin monkeys in Brazil using heavy stones to break open aged palm nuts.

Related: Chimps Used Stone HammersBird Using Bait to FishOrangutan Attempts to Hunt Fish with SpearDolphins Using Tools to Hunt

Fungus-gardening Ant Species Has Given Up Sex Completely

The complete asexuality of a widespread fungus-gardening ant, the only ant species in the world known to have dispensed with males entirely, has been confirmed by a team of Texas and Brazilian researchers.

photo of christian rabeling excavating ants in BrazilGraduate student Christian Rabeling excavating fungus-farming ant nests in Brasilia.

Most social insects—the wasps, ants and bees—are relatively used to daily life without males. Their colonies are well run by swarms of sterile sisters lorded over by an egg-laying queen. But, eventually, all social insect species have the ability to produce a crop of males who go forth in the world to fertilize new queens and propagate.

Queens of the ant Mycocepurus smithii reproduce without fertilization and males appear to be completely absent, report Christian Rabeling, Ulrich Mueller and their Brazilian colleagues in open access journal PLoS ONE this week.

“Animals that are completely asexual are relatively rare, which makes this is a very interesting ant,” says Rabeling, an ecology, evolution and behavior graduate student at The University of Texas at Austin. “Asexual species don’t mix their genes through recombination, so you expect harmful mutations to accumulate over time and for the species to go extinct more quickly than others. They don’t generally persist for very long over evolutionary time.”

Previous studies of the ants from Puerto Rico and Panama have pointed toward the ants being completely asexual. One study in particular, by Mueller and former graduate student Anna Himler (now at Arizona State University), showed that the ants reproduced in the lab without males, and that no amount of stress induced the production of males.

Scientists believed that specimens of male ants previously collected in Brazil in the 1960s could be males of M. smithii. If males of the species existed, it would suggest that—at least from time to time—the ants reproduce sexually.

Rabeling analyzed the males in question and discovered that they belonged to another closely related (sexually reproducing) species of fungus-farmer, Mycocepurus obsoletus, thus establishing that no males are known to exist for M. smithii. He also dissected reproducing M. smithii queens from Brazil and found that their sperm storage organs were empty.

Taken together with the previous studies of the ants, Rabeling and his colleagues have concluded that the species is very likely to be totally asexual across its entire range, from Northern Mexico through Central America to Brazil, including some Caribbean islands.

As for the age of the species, the scientists estimate the ants could have first evolved within the last one to two million years, a very young species given that the fungus-farming ants evolved 50 million years ago.

Rabeling says he is using genetic markers to study the evolution and systematics of the fungus-gardening ants and this will help determine the date of the appearance and genetic mechanism of asexual reproduction more precisely in the near future.

Full press release

Related: Bdelloid Rotifers Abandoned Sex 100 Million Years AgoAmazonian Ant Species is All Female, Reproduces By CloningFemale Sharks Can Reproduce AsexualityAmazon Molly Fish are All Female

Anthropologists Find New Type of Urbanism in Amazon Jungles

Anthropologists Find New Type of Urbanism in Amazon Jungles

Recently-discovered Amazonian settlements could be a new type of metropolis, unseen elsewhere in the world and hidden until recently in the Kuikuro jungle, say anthropologists.

Revealed by overgrown earthworks, the 100 square-mile urban units consist of clusters of interconnected villages ranging from 50-150 acres in size. The town-nodes were arranged along a highly-regular pattern of roads built around a central plaza about 500 feet across. The cities appear to have been at their height between the 13th and 17th centuries.

“No single Xingu settlement merits the term ‘city.’ But what do you do with a core of five settlements are few kilometers away from each other?” Michael Heckenberger, a University of Florida anthropologist currently in Brazil, told Science. “A fast walk from one to another would take you 15 minutes, maximum.”

Related: Aztec MathSurfing a Wave for 12 kmTraffic Congestion and a Non-Solution‘Hobbit’ human is a new species

Ranking Universities Worldwide

The Webometrics Ranking of World Universities provides another estimate of the top universities. The methodology is far ideal however I still find it interesting. The various attempts to rank schools can provide a general idea of impact of various institutions (though the measures are fairly crude). Still a sensible picture (especially at the country level) can emerge. And the various rankings should be a able to track shifts in the most influential institutions and relative country strength over time. How quickly those rankings track changes will vary depending on the measures used. I would imagine most will lag the “real” changes as it is easy to imagine many measures that would lag. Still, as I have said before, I expect the USA will lose in relative ranking compared to China, India, Japan, Singapore, Mexico…

The ranking methodology used here weighed rankings in: Jiao Tong academic rankings, Essential Science Indicators, Google Scholar, Alexa (a measure of web site visits to universities) and The Times Higher World University Rankings.

Country representation of the top universities (number of top schools in each country):

location Webometrics
Top 100
Jiao Tong
Top 101
% of World
Population
% of World GDP*
USA 53 54   4.6%   30.4%
Germany 10   5  1.3   6.3
Canada   8   4  0.5   2.5
United Kingdom   6 10  0.9   5.0
Australia   3   2  0.3   1.6
Japan   1   6 2.0 10.3
The rest of Europe 16 13
Brazil   1   0   2.8   1.8
Mexico   1   0   1.6   1.7
Israel   0   1   0.1   0.3

* IMF, World Economic Outlook Database, September 2006 (2005 data)
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