How To Help a Lost Dolphin Bang on some pipes or just use a pinger instead. By Jacob Leibenluft A group of about 15 bottlenose dolphins that have been swimming in New Jersey's Shrewsbury River since mid-June now appears to be moving farther inland. Local marine officials had originally planned to coax them out of the river, but they have shelved those plans for now. How would you coax a dolphin back into the ocean, anyway? With nets or noise—but both methods can be dangerous. Nets have been used to save dolphins before, usually by deploying divers to ensnare the dolphin, removing the animal from the water with a special stretcher, and quickly transporting it to safety. But capturing the dolphin is not always an easy feat, and there's also the possibility the animal will get entangled in the webbing and drown. An alternative is to create a barrier upstream using boats and then bang pipes or use high-frequency pingers to scare the dolphins in the opposite direction. But this method has downsides, too. Because dolphins are so sensitive to sound, the loud noises can create a highly stressful situation. In extreme cases, the stress can even send a dolphin into shock or cause it to beach itself. Last year, an effort to rescue a group of common dolphins in Long Island's Northwest Creek using this method had mixed results: Eight dolphins were safely corralled into the Atlantic, but 11 could not be saved. Despite these risks, there are times when rescuing a dolphin is worth the danger. Keep a bottlenose dolphin too long in fresh water, and the process of osmosis can start causing serious health problems. (River dolphins do exist, but they are classified in a different family from ocean dolphins and aren't found in the United States.) After about three days in freshwater, a bottlenose dolphin's skin would begin to swell, and its corneas would become cloudy. Soon afterward, the animal might develop skin lesions, eventually leading to infections that can spread throughout its body. (To see a case study of one bottlenose dolphin rescued from a Florida river, click here.) Fortunately for the dolphins in New Jersey, they have been swimming in the Shrewsbury and the neighboring Navesink—two bodies of water that are better described as estuaries rather than rivers. Estuaries contain a brackish mix of freshwater and seawater that is probably salty enough to keep the dolphins in good health: Veterinarians say dolphins can get in trouble when salinity levels drop below 15 parts per thousand; measurements near the bridge the dolphins recently passed under were more than 25 parts per thousand on Thursday. These particular dolphins may also be well-suited to water with a slightly lower salinity content, since they appear to be part of a stock that sticks closer to the land even when they aren't lost. (Marine biologists believe the dolphins may have been attracted inland by schools of menhaden, a fish the animals prey on.) But no matter the salt content, these estuaries could be dangerous come winter: Back in 1993, a group of four dolphins that stayed in the frozen Shrewsbury River until December died after rescuers tried unsuccessfully to free them from the ice.

What's So Exotic About an "Exotic Loan"? Its zany repayment plan. By Juliet Lapidos The Federal Reserve will issue new lending rules to "restrict exotic mortgages" for people with poor credit ratings, according to a report in Tuesday's New York Times. What's so exotic about an exotic mortgage? Its nontraditional repayment plan. Under a conventional mortgage, a borrower pays back part of the loaned money each month, along with interest. A borrower who takes out an "exotic" or "alternative" loan, by contrast, can put off paying back the principal. With an interest-only plan, or "IO," the borrower doesn't start chipping away at the principal for what is typically between three and 10 years. With a payment option adjustable rate mortgage, the borrower can choose different plans from month to month. One option is interest-only; another, called "minimum payment," cuts the borrower even more slack—he or she doesn't even have to pay the full interest every month. Another example of an exotic mortgage is the "teaser," a specific type of ARM. To entice customers, lending agencies set a low initial interest rate, then reset the interest to a much higher rate at the first agreed-upon adjustment date. In contrast, the "subprime mortgages" that keep getting mentioned in the news refer more broadly to high-interest loans issued to borrowers with low credit scores. (The high interest rate compensates for the fact that customers with damaged credit are more likely to default.) A borrower with bad credit can take out a high-interest loan on a traditional, fixed-rate repayment scheme or experiment with an "exotic" plan. Exotic loans are easier to keep up with in the short-term, but they carry significant risks for borrowers down the road. For example, someone on an IO plan may have his payments double or even triple once the interest-only period ends. A minimum payment plan can result in "negative amortization," whereby unpaid interest is added to the principal—and the aspiring homeowner ends up owing more for his mortgage than he originally borrowed. Exotic loans do make sense for certain borrowers. For example, a Wall Street banker who has a relatively modest salary but expects a large bonus at Christmas may take out a pay-option ARM, start out by making interest-only payments, and then address the principal after the holidays. In Tuesday's article on the Fed clampdown, the New York Times defines an exotic mortgage as an "Alt-A" loan, but that's not strictly correct. An Alt-A, or alternative documentation, loan holds borrowers with a good credit score to a lower approval standard than a traditional loan. (Applicants may not need to provide proof of income, for example.) So while an Alt-A is nontraditional and in that loose sense "exotic," an exotic loan isn't necessarily an Alt-A.

Do Fireworks Cause Air Pollution? Air quality on the Fourth of July. By Jacob Leibenluft Officials in Nevada warned that July 4 fireworks—combined with smoke from California wildfires—may cause unhealthy levels of air pollution. So did the weekend fireworks cause Las Vegas to exceed clean-air standards? Yes, at least for a few hours. This isn't at all unusual: State environmental agencies often report Independence Day spikes in their PM2.5 readings—a measure of the concentration of very tiny airborne particles, no bigger than 2.5 micrometers in diameter. Under federal law, a location's air quality is judged, in part, by the number of days on which the PM2.5 average exceeds 35 micrograms per cubic meter. Fireworks shows on the Fourth of July can put out enough pollution to break that threshold. In Las Vegas, preliminary data from at least one site shows PM2.5 readings greater than 200 micrograms per cubic meter at 10 p.m. on July 4. The city's air quality was clean enough earlier in the day to prevent the 24-hour average from cracking 35, so the show won't affect the city's clean-air record. In other places, the average reading might have been higher. Last year, for example, an air-quality monitor located in South Bend, Ind., registered an average reading of 39 micrograms per cubic meter on July 4, up from 16.6 the day before. Fireworks-related pollution may not affect a city's air-quality rankings, even if the average readings do surpass the federal threshold. That's because the Environmental Protection Agency has a special provision allowing states to discount a high reading in the case of "exceptional events." This is supposed to ensure that unforeseen events like wildfires or terrorist attacks don't artificially boost a location's air-pollution readings. Because the agency classifies July 4 fireworks as a special cultural tradition, state and local agencies can apply to have their abnormally high readings struck from the record. (Chinese New Year fireworks are exempt, too.) Last year, cities including Fresno, Calif., (PDF) and Salt Lake City (PDF) filed reports explaining why July 4 readings shouldn't count toward their stats. These reports also make a clear case that the higher pollution levels are due to the fireworks themselves and not a spike in automobile traffic for the holiday. Fireworks-related air pollution is not a uniquely American problem. One team of scientists in India reported that sparklers set off during the Diwali festival raise ozone levels; another recorded sulfur dioxide concentrations as much as 10 times higher during the holiday. A Chinese study found similar results during a lantern festival in Beijing. Research suggests (PDF) that weather conditions make a big difference, too: If the wind is weak, then the particles released during the fireworks display will take longer to disperse.

The 500,000 Artifacts of George Washington How did archaeologists find half a million objects at one site? By Jacob Leibenluft Archaeologists announced on Wednesday that they had unearthed George Washington's boyhood home at a site not far from Fredericksburg, Va. Over the course of a seven-year excavation, the researchers found more than 500,000 artifacts. How can there be half a million artifacts at one site? Almost everything you find counts as an artifact, as long as it was made or impacted by people. The objects comprise more than just materials from George Washington's home; archaeologists excavated a full acre of land, and the items they collected spanned 10,000 years of history—from rocks used to sharpen prehistoric stone tools to Civil War-era buttons. The collection does include an expensive tea set thought to be owned by the Washingtons and a pipe bearing a Masonic crest, but most of the objects are far more mundane, like nails, broken glass, or cracked egg shells. The only artifacts that weren't removed from the site are remnants of old buildings—either architectural fragments that are still intact or foundation stones that were weighed and left at the site. Once the artifacts are excavated, the archaeologists clean, examine, and identify them in the lab. Each item is cataloged in a computer database with a number and an "address" that denotes where exactly it was found. Most are then put in a plastic bag, placed in a protective box, and shelved in a storage room—with the finds organized by their original location at the site. It's standard professional practice to store all these artifacts. (It isn't unusual for an archaeologist to collect millions over the course of a career.) If an archaeologist leaves an object at the site after it has already been dug up, the artifact can't be easily reanalyzed by future researchers. So even if an archaeologist were only interested in George Washington's old toys, he or she would still be expected to carefully collect, catalog, and store anything found closer to the surface. A researcher who violates these rules can be investigated for misconduct and removed from the Register of Professional Archaeologists. An archaeologist must also ensure that there are "adequate curatorial facilities for specimens and records" before he starts digging. That is no easy task, and the need for so much storage space has led to what some in the field have called a "curation crisis." Keeping millions of objects has become increasingly expensive: A 2003 study by the National Park Service found that some museums charge as much as $1,000 per box for storage. That has led to a discussion of whether and how collections should "deaccession" (i.e., get rid of) objects like tin cans or old soil samples.

Secret Muslims Are Muslims allowed to hide their faith? By Juliet Lapidos According to a poll published in March, one in 10 registered voters believes that Barack Obama is a Muslim. He's not—the presumptive Democratic nominee for president is a Christian—but this rumor got the Explainer wondering whether there's a history of Muslims who deny their faith publicly while maintaining it privately. Are Muslims allowed to pass? Yes, if you're a Shiite; maybe, if you're a Sunni. According to Chapter 16, Verse 106 of the Quran, "Any one who, after accepting faith in Allah, utters Unbelief—except under compulsion, his heart remaining firm in Faith—but such as open their breast to Unbelief, on them is Wrath from Allah, and theirs will be a dreadful Penalty." Shiites cite this verse to justify taqiyya, a religious dispensation by which persecuted Muslims may hide their beliefs. But Sunni scholars have a more equivocal take. Some reject taqiyya as unacceptable hypocrisy and evidence of cowardice: Muslims shouldn't fear other humans, only Allah. Others argue that concealment is warranted under life-threatening circumstances. The difference in interpretation may have to do with the historical relationship between the two Islamic sects. Since Shiites make up just 15 percent of the global Muslim population, they have sometimes faced persecution as a minority group. (Sunnis are the minority in certain countries, including Iran and Azerbaijan.) As a result, Shiite leaders have for centuries allowed followers to dissimulate publicly rather than face discrimination. Some Muslims would argue that it's better to run away than hide your faith, citing Chapter 4, Verse 97 of the Quran: "Those whose lives are terminated by the angels, while in a state of wronging their souls, the angels will ask them, 'What was the matter with you?' They will say, 'We were oppressed on earth.' They will say, 'Was God's earth not spacious enough for you to emigrate therein?' For these, the final abode is Hell, and a miserable destiny." According to one interpretation of this verse, those who can't practice Islam freely and publicly should simply move to a more hospitable country. Outside the Islamic world, there are two major historical examples of Muslims practicing taqiyya. During the 16th century, Catholic authorities in Spain gave the local (predominantly Sunni) Muslim population an ultimatum: Convert or leave the country. Some of the converts (called Moriscos by the Spanish) became sincere Catholics while others perpetuated their faith in private. Crypto-Muslims attended church services on Sundays but used Aljamiado—an Arabic alphabet for transcribing Romance languages—to secretly pass down Islamic traditions. In antebellum America, slaves from West Africa, many of whom were Muslim, were forced to convert to Christianity. As in medieval Spain, some slaves converted sincerely while others maintained their religion in secret.