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An exotic particle made up of five quarks has been discovered a decade after experiments seemed to rule out its existence. The short-lived ‘pentaquark’ was spotted by researchers analysing data on the decay of unstable particles in the LHCb experiment at the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics laboratory near Geneva. The finding, says LHCb spokesperson Guy Wilkinson, opens a new era in physicists’ understanding of the strong nuclear force that holds atomic nuclei together....

By Paulo PradaRIO DE JANEIRO (Reuters) - Heavy rains late Tuesday and early Wednesday paralyzed much of Rio de Janeiro, a tropical metropolis scrambling to improve infrastructure to prepare to host the 2014 World Cup and the 2016 Olympics.More rain fell overnight around the city, Brazil’s second biggest, than would normally be expected during the entire month, meteorologists said. The downpour flooded major thoroughfares, toppled houses in working class suburbs, disrupted train and flight schedules and created such chaos that Mayor Eduardo Paes asked residents to stay home....

For years the birth control methods collectively known as periodic abstinence have been jokingly referred to as “Vatican roulette,” a nod to the fact that these techniques are both Vatican approved and quite likely to end in pregnancy. (The World Health Organization reports that on average, women practicing periodic abstinence for a year have a one in four chance of becoming pregnant.) A new German study, however, has found that, when practiced correctly, a method of periodic abstinence known as the sympto-thermal method (STM) leads to an unintended pregnancy rate of only 0....

Nearly half of all college math majors are women, and females now score as well as males on standardized math tests. Yet only about 30 percent of Ph.D.s in mathematics—and fewer in computer science, physics and engineering—are awarded to women every year, and men far outnumber women in science- and math-related tenure-track positions at U.S. universities. Why? For decades researchers have blamed sex discrimination and bias, but research suggests that there may now be a less sinister culprit: motherhood....

Most of us grew up with a rather placid notion of the formation of our solar system: dust agglomerating into larger clumps, with an “ice line” forming the divide between the outer behemoths like Jupiter that we see today against the smaller, rockier bodies orbiting closer to our sun. Then astronomers began to find exoplanets multiple times the size of Jupiter—and generally far too close to their stars to fit within our tidy classical theories....

A newfound species of millipede has more legs than any other creature on the planet—a mind-boggling 1,300 of them. The leggy critters live deep below Earth’s surface and are the only known millipedes to live up to their name. “The word ‘millipede’ has always been a bit of a misnomer,” said Paul Marek, an entomologist at Virginia Tech university and lead author of the study describing the newfound species. All other known millipedes Millipedes sport far fewer legs than their name implies, with many species having fewer than 100 legs....

Political scientists are usually busy in early August, polishing proposals for grants from the National Science Foundation (NSF). But not this year. Less than one month before an annual mid-August application deadline, the funding agency has scrapped new political-science funding for the rest of 2013. The NSF declines to explain its reasons for eliminating the grant call, one of two that typically take place each year. But leaders in the field are blaming Congress, which on 21 March passed a bill requiring that NSF-funded political-science research benefit either national security or economic interests....

All pandemics end eventually. But how, exactly, will we know when the COVID-19 pandemic is really “over”? It turns out the answer to that question may lie more in sociology than epidemiology. As the world passes the second anniversary of the World Health Organization’s declaration of the COVID pandemic, things seem to be at a turning point. COVID cases and deaths are seeing sustained declines in much of the world, and a large percentage of people are estimated to have some immunity to SARS-CoV-2, the virus that causes the disease, through infection or vaccination....

Two researchers say they have built a cylinder that acts as an ersatz electromagnetic black hole, soaking up radiation in the microwave regime like the astrophysical version sucks up matter and light. Qiang Cheng and Tie Jun Cui of the State Key Laboratory of Millimeter Waves at Southeast University in Nanjing, China, detailed their creation in a paper posted to the online physics preprint Web site arXiv.org last week. Cheng and Cui report engineering a thin cylinder 21....

Key concepts Perception Optical illusions Human biology Space Introduction Have you ever noticed how the moon appears much bigger at the horizon, just as it is rising over the nearby buildings or treetops, than it does later in the evening when it is directly overhead? Of course, the moon’s size does not change, but our perception of its size changes based on its position in the sky. In this activity you’ll investigate Emmert’s law, which helps explain the full-moon illusion, and estimate the size of the perceived increase in size of the moon when it is near the horizon....

A discovery that two commonly used food additives are estrogenic has led scientists to suspect that many ingredients added to the food supply may be capable of altering hormones. More than 3,000 preservatives, flavorings, colors and other ingredients are added to food in the United States, and none of them are required to undergo testing for estrogenic activity, according to the Food and Drug Administration. “We need to be mindful of these food additives because they could be adding to the total effect of other estrogen mimicking compounds we’re coming into contact with,” said Clair Hicks, a professor of food science at the University of Kentucky and spokesperson for the Institute of Food Technologists, a nonprofit scientific group....

Key concepts Temperature Mathematics Energy Chemical reactions Insects Sound Introduction Do you love to hear the pulsing chirp of crickets as you fall asleep? It is an unmistakable sound. Some people find the sound pleasing and peaceful whereas others find it loud and annoying, especially if a cricket happens to find refuge from the cold inside a home. However you feel about crickets, their chirps hold a surprising message—they can report the temperature!...

By Nicola NosengoDrilling deep into the heart of an active volcano might sound dangerous, but a team of scientists say that it could prove vital to protecting the Italian city of Naples from a potentially devastating eruption.Early next month, researchers will begin to sample rocks and install underground sensors inside Campi Flegrei, a giant volcanic formation in southern Italy. They hope to learn where the magma is stored and what signs might precede an eruption....

In a 1997 episode of The Simpsons entitled “The Springfield Files”—a parody of X-Files in which Homer has an alien encounter in the woods (after imbibing 10 bottles of Red Tick Beer)—Leonard Nimoy voices the intro as he once did for his post-Spock run on the television mystery series In Search of…: “The following tale of alien encounters is true. And by true, I mean false. It’s all lies. But they’re entertaining lies, and in the end isn’t that the real truth?...

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. What is the Third Estate? was a pamphlet published by Abbè Emmanuel-Joseph Sieyès (1748-1836) in January 1789, months before the start of the French Revolution (1789-1799). The pamphlet concerns the place of the Third Estate (commoners) within the French nation, as well as what it should hope to gain from the Estates-General of 1789....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. The sculpture group of Laocoön and His Sons, on display in the Vatican since its rediscovery in 1506 CE, depicts the suffering of the Trojan prince and priest Laocoön (brother of Anchises) and his young sons Antiphantes and Thymbraeus and is one of the most famous and fascinating statues of antiquity....

Did you like this article? Editorial Review This article has been reviewed for accuracy, reliability and adherence to academic standards prior to publication. In 1845 CE, the archaeologist Austen Henry Layard began excavations at the ruins of the city of Nimrud in the region which is northern Iraq in the present day. Layard’s expedition was part of a larger movement at the time to uncover ancient sites in Mesopotamia, which would corroborate stories found in the Bible, specifically in books in the Old Testament such as Genesis and Jonah....

Rebecca Robinson does not wear gloves on the job. A misstep while removing them, she says, could increase the risk of infecting herself with Ebola. Instead, she dons a rain jacket and boots and clutches a bottle of hand sanitizer as she travels by motorbike from house to house in Liberia’s capital city of Monrovia. Her objective: to help trace the complex web of Ebola’s spread and to instruct apparently healthy people who may have had contact with an infected person to stay home for 21 days....

When the majority of stars reach the end of their life, they make their own funeral pyre, throwing off most of their remaining gas in a glorious last display of their immense power and leaving behind a dense, cinderlike core known as a white dwarf. But what becomes of any planets orbiting such a star? This question has been difficult to answer, but now scientists say they have detected the suspected remnant of a white dwarf world, a first-of-its-kind discovery that could offer fascinating insights into planetary systems’ dying days across the universe....

A European rocket is ready to launch the most ambitious mission ever taken towards Mercury, Earth’s once-neglected sibling in the Solar System. The €1.6-billion (US$1.85-billion) expedition, carrying 2 robotic orbiters, ranks among the most expensive missions undertaken by the European Space Agency, and it includes Japan’s largest contribution yet to an international collaboration in space. If all goes according to schedule, BepiColombo will lift off in the late hours of 19 October from the Kourou spaceport in French Guiana, atop an Ariane 5 heavy-launch vehicle....