Steph Yin

<h1>Lunar New Year kicked off Tuesday as one of the most important holidays in Vietnam, South Korea, China and other Asian countries. Typically, it starts on the second new moon after winter solstice.</h1>

On the Gregorian calendar, the civil calendar used in most countries, including the United States, the Lunar New Year changes every year, as do the dates of holidays like Rosh Hashana, Diwali and Ramadan.

It can be easy to think of a calendar as a scientific given, or a reflection of the laws of the universe. In fact, as these holidays remind us, there are as many ways to track time as there are cultures and languages. Each calendar reveals something about how the people who created it relate to the world around them while also preserving rich cultural identities and memories.

Most timekeeping traditions track the movement of the sun, moon and stars. Others consider seasonal events, like the autumnal swarming of sea worms, used to orient each year in the Trobriand Islands off New Guinea, or the flowering of immortelle trees into hundreds of tiny vermilion flames, which marks the start of the dry season in Trinidad.

With any calendar, the basic question is which of thousands, if not millions, of cycles in the world to follow, said Kevin Birth, an anthropology professor at Queens College. Calendars “always come down to this cultural choice,” he said, so using one system over another is ultimately a social contract, regardless of how scientifically accurate or sophisticated a calendar is.

A solar year — the time it takes Earth to orbit the sun — lasts around 365 days, while a lunar year, or 12 full cycles of the moon, is roughly 354 days. Because of this discrepancy, a purely lunar calendar — like the Islamic, or Hijri, calendar — doesn’t stay aligned with the seasons. Islam’s holy month of Ramadan may fall in summer one year, and winter a number of years later.

To correct for seasonal drift, the Chinese, Hindu, Jewish and many other calendars are lunisolar. In these calendars, a month is still defined by the moon, but an extra month is added periodically to stay close to the solar year.

A solar calendar is useful for farming, fishing and foraging societies that need to plan ahead for particular times of the year. But a purely solar calendar, like the Gregorian, tells you nothing about the phases of the moon.

The traditional Hijri calendar requires an observation of the early crescent moon to start a new month, and thus encourages paying attention to the cosmos. The Gregorian calendar can’t be tracked in the sky, which might be why many Westerners have less awareness of the moon and other natural phenomena, said Sacha Stern, a professor of Hebrew and Jewish Studies at University College London.

Major events on the calendar shape cultural identity. When Jews around the world celebrate Sukkot, a harvest festival, they are observing the timing of the harvest in Israel, and preserving a connection throughout the diaspora, Birth said.

Holidays also structure personal and historical narratives. Some secular holidays in the United States center on legacies of war, which fits “when you think that the United States also has the largest military budget in the world," Birth said. Chinese holidays usually emphasize family union and honoring ancestors, Yuan said, which aligns with the importance of filial piety.

Many ancient calendars, like the Chinese and Mesoamerican ones, build in fortunetelling, with prescriptions for when to build a house, get married, have a funeral and other life events. Similar calendars provide structure and comfort to people today. Britt Hart, an astrologer based in Philadelphia, said she thinks people can be drawn to horoscope-based calendars because they’re seeking a grander sense of time and order in the universe.

In the context of history, staying connected to an alternative calendar can also be a form of resisting the mainstream, or maintaining an identity outside of it. When a calendar is imposed on a society, it usually has to do with politics and power. The ability “to say when the year will start, or decide that a religious festival should be celebrated at a particular time, can be quite useful for a politician,” Stern said.

The Gregorian calendar has only been used as a global standard for about a century, and is “very much a reflection of European commerce and colonialism,” Birth said. It has now been built into computer architecture, but that doesn’t mean another calendar couldn’t one day become dominant.

A Hijri calendar from the Gregorian year 2014 hangs in Birth’s office. On it, Christmas falls on 3 Rabi al-Awwal, the third day of the third month.

He loves the reminder that, “holidays you think are stationary actually move, and those you think move are actually stationary.” It shows “how cultural these things are, rather than natural,” he said.

This article originally appeared in <a id="c58c231a-8be3-44a4-aa97-4f022112c6d1" href="https://www.nytimes.com/2019/02/05/science/chinese-new-year-lunar-calendar.html">The New York Times</a>.

Celebrating Lunar New Year and the Diversity of the World's Calendars

On the Gregorian calendar, the civil calendar used in most countries, including the United States, the Lunar New Year changes every year, as do the dates of holidays like Rosh Hashana, Diwali and Ramadan.

Celebrating Lunar New Year and the diversity of the world's calendars

Lunar New Year kicked off Tuesday as one of the most important holidays in Vietnam, South Korea, China and other Asian countries. Typically, it starts on the second new moon after winter solstice.

A solar year — the time it takes Earth to orbit the sun — lasts around 365 days, while a lunar year, or 12 full cycles of the moon, is roughly 354 days. Because of this discrepancy, a purely lunar calendar — like the Islamic, or Hijri, calendar — doesn’t stay aligned with the seasons. Islam’s holy month of Ramadan may fall in summer one year, and winter another.

Many ancient calendars, like the Chinese and Mesoamerican ones, build in fortunetelling, with prescriptions for when to build a house, get married, have a funeral and other life events. Similar calendars provide structure and comfort to people today. Britt Hartt, an astrologer based in Philadelphia, said she thinks people can be drawn to horoscope-based calendars because they’re seeking a grander sense of time and order in the universe.

This article originally appeared in <a href="https://www.nytimes.com/2019/02/05/science/chinese-new-year-lunar-calendar.html" id="fada750e-4f1b-3b74-acfb-14f6e380129b">The New York Times</a>.

(Trilobites)

The axolotl, sometimes called the Mexican walking fish, is a cheerful tube sock with four legs, a crown of feathery gills and a long, tapered tail fin. It can be pale pink, golden, gray or black, speckled or not, with a countenance resembling the “slightly smiling face” emoji. Unusual among amphibians for not undergoing metamorphosis, it reaches sexual maturity and spends its life as a giant tadpole baby.

According to Aztec legend, the first of these smiling salamanders was a god who transformed himself to avoid sacrifice. Today, wild axolotls face an uncertain future. Threatened by habitat degradation and imported fish, they can only be found in the canals of Lake Xochimilco, in the far south of Mexico City.

Captive axolotls, however, are thriving in labs around the world. In a paper published Thursday in Genome Research, a team of researchers has reported the most complete assembly of DNA yet for the striking amphibians. Their work paves the way for advances in human regenerative medicine.

Many animals can perform some degree of regeneration, but axolotls seem almost limitless in their capabilities. As long as you don’t cut off their heads, they can “grow back a nearly perfect replica” of just about any body part, including up to half of their brain, said Jeramiah Smith, an associate professor of biology at the University of Kentucky and an author of the paper. To understand how they evolved these healing superpowers, Smith and his colleagues looked to the axolotl’s DNA.

At 10 times the size of the human genome, the axolotl genome was no small beast to tackle. “This thing’s huge,” said Melissa Keinath, a postdoctoral fellow at the Carnegie Institution for Science in Baltimore and an author of the paper.

Building off a previous study, Keinath and her colleagues mapped more than 100,000 pieces of DNA onto chromosomes, the structures that package DNA in the nucleus of each cell. Their axolotl genome is the largest genome to be assembled at this level.

The scientists used an approach called linkage mapping, which relies on the fact that DNA sequences that are physically close together on a chromosome tend to be inherited together.

To identify axolotl-specific DNA, the researchers juxtaposed axolotls with tiger salamanders, which are close relatives. Specifically, they crossed axolotls and tiger salamanders, then backcrossed these first-generation hybrids with pure axolotls.

Tracking patterns of gene inheritance across 48 of these second-generation hybrids, the researchers were able to infer which sequences of DNA belonged to axolotls and where they physically sat along the amphibian’s 14 chromosomes (humans have a greater number of chromosomes, but the axolotl’s are much larger).

It was like “putting together 14 linear puzzles,” said Randal Voss, a professor of neuroscience at the University of Kentucky and an author of the study.

In the process of validating their results, they identified a gene mutation that causes a commonly studied heart defect in axolotls, demonstrating that their research will speed up the process of scanning the axolotl genome for mutations in the future.

Ultimately, knowing how DNA is positioned along chromosomes “allows you to start thinking about functions and how genes are regulated,” Voss said. For instance, much of the genome consists of noncoding DNA sequences that turn genes on and off. Often, these noncoding sequences occur on the same chromosome as the genes they interact with.

“Once these relationships are known, then we can ask questions about whether the same kind of controls happen in other animals, like humans,” said Jessica Whited, a professor and limb regeneration expert at Harvard Medical School who was not involved in the study.

Overall, she added, that will help scientists understand whether there are predictable ways to “render humans more like axolotls,” fantastic regenerators of the animal kingdom.

This article originally appeared in <a href="https://www.nytimes.com/2019/01/29/science/axolotl-dna-genome-sequence.html" id="546df7c3-6d2a-3916-ac26-6f4be7e0a6b1">The New York Times</a>.

Seeking Superpowers in the Axolotl Genome

<h1>Anita Radini, an archaeologist at the University of York, in England, spends a lot of time looking at tartar. Really old tartar.</h1>

Tartar, or dental plaque — that film of bacteria that feels like sweaters on your teeth — contains a wealth of information about what long-dead individuals encountered in their daily lives. Radini has seen all sorts of things trapped in it: food particles, textile fibers, DNA, pollen, bacteria and even wings of tiny insects.

But several years ago, when studying the dental plaque of a nun from medieval Germany, Radini saw something entirely new: particles of a brilliant blue. She showed the findings to Christina Warinner, another tartar expert, who was shocked.

“They looked like little robins’ eggs, they were so bright,” said Warinner, group leader of archaeogenetics at the Max Planck Institute for the Science of Human History in Germany. “I remember being dumbfounded.”

The scientists put together a multidisciplinary team of scholars and set out to unravel the origins of this blue dust. The results, described in a paper published Wednesday in Science Advances, far exceeded the team’s expectations.

The particles, it turned out, were of ultramarine pigment, the finest and most expensive of blue colorings, made of lapis lazuli stone from Afghanistan. The German nun with the pigment in her teeth — B78, as she is known in the archaeological literature — was likely a painter and scribe of religious texts. And she must have been highly skilled to have been entrusted with such a rare powder, the researchers said.

The finding upends the conventional assumption that medieval European women were not much involved in producing religious texts. “Picture someone copying a medieval book — if you picture anything, you’re going to picture a monk, not a nun,” said Alison Beach, a historian at Ohio State University, and an author on the study.

The skeleton of B78 dates to sometime between 997 and 1162 A.D. The nun was probably 45 to 60 years old when she died, and was buried in an unmarked grave near a women’s monastery in Dalheim, Germany. Historians know little else about the site, because almost all of it was destroyed by a fire in the 14th century.

Radini first noticed traces of blue when she immersed a sample of B78’s tartar in a weak acid solution. Scientists use this method to dissolve calcified tartar, so they can study any remaining food, pollen or other particles.

Most scientists would have walked away and let the solution dissolve overnight. But Radini stayed and watched for a bit, to make sure the process was going properly. Under the microscope, she was surprised to see blue particles tumbling out of the tartar’s matrix. By morning, the color was gone.

Mineral pigments tend to lose their color in acids, so Radini had to figure out a way to extract and preserve the blue pigment. The method that worked best involved putting the plaque in a bath of ultrapure water and using high frequency sound waves to break apart the matrix.

Through a series of experiments, the team identified the particles. Monica Tromp, a microscopist at the Max Planck Institute for the Science of Human History, used scanning electron microscopy to show that the pigment had all the chemical elements of lapis lazuli. Roland Kröger, a physicist at the University of York, used spectroscopy to confirm the structure of two minerals, lazurite and phlogopite, that are only found together in lapis lazuli. That was “a smoking gun,” Warinner said.

At the time, blue pigment “was as, or more, valuable than the gold applied to manuscripts,” Beach said. Only 5 percent of the lapis lazuli used in the production process is converted into pigment, and the stone would have had to travel through thousands of miles of trade routes to reach Europe.

The pigment likely ended up on the woman’s teeth as she used her mouth to shape her paintbrush. The researchers found ultramarine layered throughout B78’s dental plaque, which suggests she painted many books in her lifetime.

“We struggle to find sources reflecting women’s lives in the Middle Ages that aren’t filtered through men’s experiences or opinions about what women’s lives should have been,” Beach said. “Now, we have a direct piece of evidence about what this woman did on a day-to-day basis — all because they didn’t brush their teeth.”

“I have a new relationship with my Sonicare now.”

This article originally appeared in <a id="2e8fc2c9-d6ee-42d2-9639-9b2ea8462544" href="https://www.nytimes.com/2019/01/09/science/10-archaeology-teeth-painting.html">The New York Times</a>.

Tartar, or dental plaque — that film of bacteria that feels like sweaters on your teeth — contains a wealth of information about what long-dead individuals encountered in their daily lives.

A woman's work was sometimes blue

<h1>Deborah Westbrook, a lifelong resident of Detroit, would love a tree in front of her home.</h1>

“With a green tree in front of my house,” she said, “and me looking at the green leaves, knowing that the tree and sun were mixing together to give off the oxygen we breathe? I would be proud. A tree in front of my house would not only help with the air, but it would help with me.”

Nonetheless, when representatives from a local nonprofit came to plant trees on her block five years ago, Westbrook said no. So did more than 1,800 Detroiters — a quarter of all eligible residents — between 2011 and 2014.

Why the high rejection rate? In a study published Monday in Society and Natural Resources, researchers found that the opposition does not arise from a dislike of trees per se. Most residents, the study found, appreciate the benefits of trees; these include alleviating air pollution, stormwater runoff and higher urban temperatures, and helping to reduce stress, crime and noise. Low-income and minority residents often live in areas with the lowest tree cover.

The researchers, led by Christine Carmichael, a postdoctoral associate at the University of Vermont, conducted interviews with more than 40 Detroit residents. The biggest predictor of whether someone declined a tree, it turned out, was whether that person had negative experiences with trees — or with city workers or outsiders who, as one respondent said, “come in and try to ‘do good,’ but only half do the job.”

From the end of the 19th century until the 1950s, Detroit was known as “the city of trees,” with more per capita than any industrialized city in the world. But by 1980, more than half a million trees had died. Of the 20,000 trees marked dead or hazardous in 2014, when Carmichael’s study began, the city had removed only 2,000 or so.

Westbrook noted that the city hasn’t addressed several dead trees on her block. She was worried that a dead giant next door would damage her roof, leaving her to pay for repairs. Now retired, Westbrook worked for Detroit’s water department, where she saw enough tree roots growing into pipes that she didn’t want to plant a tree of her own until she replaced her old pipes with root-resistant PVC ones.

Other cities have encountered similar resistance to their tree-planting efforts. “Some poor decisions were made around trees that were planted 50 years ago,” said Kathryn Ott Lovell, Philadelphia’s parks and recreation commissioner. The city’s TreePhilly program, which helps residents plant and care for trees, offers up to a dozen types of trees as options and explains which trees are safe to plant around pipes, sidewalks and wires.

Carmichael has offered recommendations based on her research. Residents should be involved in at least choosing the type of tree they receive. Agencies should shift their metrics of success to include not just the number of trees planted, but also how engaged residents are in the process. Based on those suggestions, The Greening of Detroit, the nonprofit group that came to Westbrook’s neighborhood, expanded its youth employment program, which trains and gives stipends to local high school students to maintain and teach residents about trees.

Although Westbrook turned down a tree, her block is fairly lush. Neighbors collectively maintain bushes and flower beds on the block’s corners, and they’ve taken up the task of watering trees. The trees planted in 2014 by Greening of Detroit “are well-rooted and they are growing,” said Mellow Jean Dixon, Westbrook’s neighbor, who has one next to her house.

She added, “I think, if need be, we would get together and take care of any tree we saw that needed taking care of.”

Most of the blocks’ residents have lived in their homes for a long time, and they take pride in being one of the prettier blocks around. Westbrook noted that some nearby blocks have no trees at all. “It’s like the earth is missing something,” she said.

This article originally appeared in <a id="5bf715f5-35e5-4e87-8c50-2028618e11f2" href="https://www.nytimes.com/2019/01/07/science/detroit-trees-health.html">The New York Times</a>.

Free trees? Many Detroit residents say no thanks

Why the high rejection rate? In a study published Monday in Society and Natural Resources, researchers found that the opposition does not arise from a dislike of trees per se.

Twinkling pine, spruce and fir trees bring holiday cheer to homes around the world. But with the end of festivities comes the not-so-jolly chore of disrobing and discarding these unwieldy house guests.

You don’t want your Christmas tree to end up in a landfill, where it will take forever to decompose. So what’s the most responsible way to get rid of a Christmas tree?

Usually, the Best and Easiest Way Is to Follow Your Town’s Instructions

Take a minute to search the internet for what your town recommends, or call your local trash haulers. Many communities will collect Christmas trees curbside for two or three weeks after the holidays.

Not only is this method most efficient (better to have a few garbage trucks driving around than a bunch of individual cars), but municipalities often use the trees for parks or habitat restoration, piling them into barriers against soil erosion or sinking them into ponds to provide habitat for fish. Some beachside towns use Christmas trees to rebuild sand dunes, a tactic that came in handy after Hurricane Sandy.

In New York City, the Department of Sanitation will collect your tree for mulching and “treecycling” from Wednesday through Jan. 12. Another option is to haul your tree to a MulchFest event, where you can watch it get chipped and bring home a bag of mulch.

Before you drag your shrub to the curb, make sure to strip the lights, ornaments and tinsel. If you wrap the tree in a plastic bag to get it out of the house, take the wrap off once it’s outside.

“If you leave anything on, the whole thing is garbage,” said Friday Apaliski, a sustainability coach based in San Francisco. Metal or plastic on trees can also damage choppers and potentially harm people running that machinery, she added.

If You Have to Dispose of Your Tree Yourself

Try to find a friend with a wood chipper who can shred your tree for you. “It makes wonderful compost,” said Todd Larsen, executive co-director of Green America, an environmental nonprofit based in Washington, D.C.

Alternatively, visit Earth911 and search your ZIP code for places that recycle Christmas trees. Many Home Depots, Boy Scout troops or local nonprofits will take Christmas trees at no cost.

Another good place to check is your local zoo or animal sanctuary, which might want trees for animal enrichment or food. One Michigan petting zoo, for instance, wants to turn your Christmas tree into a nutritious snack for its twin goats, Bubba and Gump.

If you’re feeling crafty, you can recycle parts of your tree to make wreaths, candles, coasters and fragrant sachets.

Finally, if you live in a rural area, you can simply put your tree out on your land and “return it to nature,” said Eric Goldstein, a lawyer for the Natural Resources Defense Council. Trees fall on their own all the time and become good habitat for birds, rodents and other wildlife.

What Not to Do

The big no-no is to chuck your tree in a bag and have it go to the landfill.

Landfills are packed so tightly that there’s no oxygen, which organic materials need to decompose, said Jessica Davis, director of the IUPUI Office of Sustainability in Indianapolis. Also, the lack of oxygen means that when your Christmas tree finally does decompose, it will release methane, a far more potent greenhouse gas than carbon dioxide.

It’s not great to burn your tree either, Larsen said. Sap and dried needles tend to crackle, pop and explode when they burn. Moreover, fir, pine and spruce trees contain a highly flammable tar called creosote, which produces soot and can lead to chimney fires.

For Next Year

Many experts agree that buying a cut tree (particularly from a local, organic farm) and recycling it is better than using an artificial tree, which can’t be recycled at the end of its life. But even better than a cut tree is a live tree that can be replanted in your yard or donated to a nearby park. Some places even rent living trees that can be returned after Christmas.

This article originally appeared in <a href="https://www.nytimes.com/2018/12/28/science/christmas-tree-disposal-recycling.html" id="334fd7d4-c340-312f-a3a5-2ef5430b6cea">The New York Times</a>.

How to Throw Away Your Christmas Tree

Scientists and engineers have been building and programming piano-playing robots for decades. But there’s something different about a new robotic hand that tickles the ivories with techniques usually reserved for humans.

Rather than relying on a maze of motors, as decades of piano bots have, the hand — introduced Wednesday in a paper in Science Robotics — operates passively, meaning its fingers are not individually connected to any motors. Instead, its design mimics human anatomy: to perform a range of actions just by way of a simple mechanical arm attached at the wrist.

“Our aim is to move away from the traditional approach in robotics, where one motor gives one behavior, because that doesn’t scale,” said Josie Hughes, a researcher in the Department of Engineering at the University of Cambridge who led the development of the hand.

Her hand, for now, is far from mastering Chopin or Debussy. But it’s capable of performing different styles and dynamics, and it can eke out a decent “Jingle Bells.”

The research is another step in the effort to design soft robots that move with the nuance of bodies, said Cecilia Laschi, a professor at the BioRobotics Institute of Scuola Superiore Sant’Anna in Italy, who was not involved in the study. Developments in this field might someday lead to robots that can explore natural environments or perform medical diagnoses by touch.

For inspiration, Hughes and her collaborators turned to the human hand.

“We don’t just have intelligence in our brain — we have intelligence distributed throughout the whole of our body,” Hughes said, adding that much of “intelligence arises from physical structure and mechanics.” For that reason, her team designed a mechanical hand with bones and ligaments placed as they are in nature.

Next, they evaluated how hard or soft different components needed to be. In the absence of motors, these varying levels of stiffness generate complexity. “We wanted to replicate how the human hand is strong and powerful, but also capable of performing light and delicate movements,” Hughes said.

The researchers fabricated the hand with a 3D printer that blended hard plastic and soft rubber in different ratios to create ligaments and joints with varying degrees of stiffness. Then they attached the hand to a robot arm that is commonly used in industrial assembly lines.

Her team broke piano playing into three types of movement: single finger strikes, jumps and sliding thumb movements. They used three musical excerpts to gauge their robot’s abilities.

The first, from “Toccata,” by Italian composer Scarlatti, requires a series of punctuated, or staccato, raps, usually performed with the index finger. The engineers found that keeping this forefinger very stiff came closest to approximating how a human would play the notes. They made the surrounding digits less stiff, to ensure that the robot could also play progressions that were soft and slurred, or legato.

Next, the researchers used “Alligator Crawl,” by American jazz pianist Fats Waller, to study their robot’s ability to play octaves. Big jumps, they found, require stretchy ligaments in the valleys between fingers but moderately stiff joints in the fingers themselves to ensure clear notes on landing.

Finally, Hughes’ team turned to the thumb, an especially complex digit. “Rhapsody in Blue,” by American composer George Gershwin, helped them model how a thumb skates across keys to create a slide in pitch, called a glissando. Low stiffness in the thumb joints — the lowest the researchers tested — helped create a smooth glissando. It also allowed the index finger to cross over the thumb, a tricky maneuver that pianists employ often to flow between keys more easily.

Compared with many previous piano bots, this one showed flexibility in volume control, thumb movements and playing both staccato and legato, Hughes said. She next plans to add sensors, motors and components that act like tendons, which will help create a wider range of behaviors.

Ultimately, she hopes to create a robot that can play piano expressively, rather than just focusing on rigid accuracy.

“We’re going beyond simply treating notes as a list of instructions,” she said. “Piano playing is an art. We’re trying to introduce that complexity, depth and artistry into our robot’s behavior.”

This article originally appeared in <a href="https://www.nytimes.com/2018/12/19/science/piano-robot-hand.html" id="8ddac4de-70f9-3eb1-aaa7-ebe1dc6d1b85">The New York Times</a>.

A Robotic Hand Plays the Piano With a More Human Touch

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