作者： chenchen

我们通过发表论文来表彰学生 STEM 写作比赛的前 10 名获奖者。这是  Daphne Zhu 的作品。

在纽约州雪莉的 Wertheim 国家野生动物保护区，被南方松甲虫蹂躏的枯死沥青松树

加州圣何塞林布鲁克高中 15 岁的 Daphne Zhu 撰写的这篇文章是学习网络第四届年度 STEM 写作比赛的前 10 名获奖者之一，我们收到了 3,000 多份参赛作品。

The Canadian Rockies loom up on both sides of the rickety road we’re bumping along. Mountains, with their high, majestic slopes lush with green forest, never fail to fill me with awe. Except this time, it’s because they’re not green. The whole mountainside is covered with the purple-gray skeletons of pine trees, branches limp, withered, dead.

A fire, I assumed — until I noticed the same view I’d seen outside the car window in a visitor center’s photograph. Pine beetles were eating through forests in the region, the caption explained, leaving barren forest habitat and a serious problem: The area of forest killed by the beetles beats the former record by 10 times. So I jumped into a library database and started reading.

The culprit of forest destruction in western Canada and even the United States lies in the mountain pine beetle. The insects burrow into pine bark and into the phloem, or food-transporting vessel, of the tree. Here, they lay their eggs; when the larvae hatch, they eat away from the inside until they move out to a new tree.

Not only do the beetles themselves carve up the pines, but spores of blue stain fungus also spread from their mouthparts into the phloem they burrow into. Fungal infection is even more effective in blocking nutrient circulation, which quickly leaves the tree to die.

The heart of the issue? Climate change.

Temperature exceeds predation as the primary factor in keeping pine beetle populations under control. Winter’s arrival used to mean that larvae, lacking cold tolerance, would die in great numbers. However, with winter temperatures warming and cold days decreasing in frequency, the beetles’ population growth is overwhelming. “It’s an exponential increase,” states Dr. Jeffrey B. Mitton, a University of Colorado professor of ecology, which means that within years, the crisis could escalate to astronomical heights.

And they’re expanding their range. The beetles conquer territory from Alaska in the north to New Mexico in the south, leaving skeleton forests in their wake. If these infestations continue to spread like spilled ink, blotting out coniferous forests across the continent, the loss will be more than that of green mountain scenery. It will be of a critical carbon sink: As the infested trees decompose, carbon dioxide stored throughout their lifetime is released. All the while, forests that once held the brakes on climate change are no longer absorbing the greenhouse gas from the atmosphere.

The Covid-19 pandemic has highlighted in bold that such diseases have the potential to wipe out millions. Unlike Covid, pine beetle infestation spares no survivors. And unlike Covid, no vaccine will boost the hosts with immunity to mitigate future attack. Besides suppressing outbreaks by removing infected trees before larvae can break out, we must commit to combating climate change. Only then will beetle populations fall back to what they were. Only then will we prevent the sight of faded mountainsides from becoming a lasting relic for future generations. Only then will we protect the longevity of the great forests of North America.

Works Cited

Embrey, Sally, MSPH, et al. “Climate Change and Ecosystem Disruption: The Health Impacts of the North American Rocky Mountain Pine Beetle Infestation.” American Journal of Public Health, May 2012.

Morgan, Korey. “Racing the Clock to Stem the Spread of the Mountain Pine Beetle.” U.S.D.A. Forest Service, 11 May 2021.

Perkins, Sid. “Book Review: Empire of the Beetle: How Human Folly and a Tiny Bug Are Killing North America’s Great Forests (David Suzuki Foundation Series) by Andrew Nikiforuk.” Science News, 7 Oct. 2011.

Robbins, Jim. “Double Trouble From Mountain Pine Beetles?” The New York Times, 19 March 2012.

我们通过发表论文来表彰学生 STEM 写作比赛的前 10 名获奖者。这是  Catherine Ji 的作品。

加利福尼亚海岸附近的一头蓝鲸。

这篇来自伊利诺伊州威尔米特市新特里尔高中的 14 岁的凯瑟琳季的文章是学习网络第四届年度 STEM 写作比赛的前 10 名获奖者之一，我们收到了 3,000 多份参赛作品。

Digging into the skin of a bowhead whale, Craig George, a biologist and researcher, heard a crunching noise. Along the coast of Alaska, beside Native whale hunters, he pulled out a perhaps century-old harpoon point from the 60-ton giant. Further discoveries found points up to 211 years old, proving the longevity of these cetaceans. Surprisingly, Dr. George did not find a single cancerous tumor. Why is it that these animals are so resistant to such a fatal disease, despite it being the second leading cause of death in humans, killing almost 10 million people annually?

Common sense tells us that, as they have around a thousand times more cells than humans, cetaceans should be more prone to cancerous mutations. Contrarily, this is not the case. Whales, elephants and other massive creatures have instead shown to be the world’s longest-living cancer-resisting mammals.

It has already been discovered that changes in whale DNA contribute to their massiveness. According to research done by Mariana Nery, “positive natural selection in four genes … correlate[s] with a bigger body.” However, these changes (mutations) also are large factors that induce cancer. These changes cause the cells to rapidly multiply and possibly inhibit organ function. Age and weight are both determinants that increase the risk of developing cancer in humans. The longer we live and the more massive we are, the more opportunity for cell mutations. First constructed by Richard Peto in 1977, Peto’s Paradox states that the chance of cancer does not correlate with the number of cells in an animal. In fact, it appears to be the opposite in cetaceans.

The answer lies in that, as whales have a much higher rate of gene mutation than other mammals (around 2.4 times), they have a high number of tumor suppressor genes, according to a study led by Daniela Tejada-Martinez and published in the Proceedings of the Royal Society B. Tumor suppressor genes are responsible for preventing cancer from developing and spreading. The study found that certain gene variants found in cetaceans “could have favored the evolution of their particular traits of anti-cancer resistance, gigantism and longevity.”

Another project led by Marc Tollis, published in the journal Molecular Biology and Evolution, implemented DNA and RNA sequencing on a skin sample from an adult female humpback whale off the coast of Massachusetts. After decoding the whale’s genome, or her complete set of DNA, the researchers compared it to other mammals. Their analyses suggested an increase in cancer-suppressing genes as well as genes that support the maintenance of healthy cells.

In an ideal world, humans can possess the same cancer-resisting abilities as whales. Carlo Maley, director of the Arizona Cancer and Evolution Center, argues that scientists may be able to “translate [their] discoveries into preventing cancer in humans.” One day, humans may be able to experiment and develop drugs based on the mammals’ biological superpowers, perhaps ending cancer’s strangling grip on the world.

Works Cited

Incorvaia, Darren. “Unlocking the Genes That Made Whales Into Giants.” The New York Times, 19 Jan. 2023.

Rozell, Ned. “Bowhead Whales May Be World’s Oldest Mammals.” The Field, 24 Nov. 2016.

Tejada-Martinez, Daniela. “Positive Selection and Gene Duplications in Tumour Suppressor Genes Reveal Clues About How Cetaceans Resist Cancer.” Proceedings of the Royal Society B, 24 Feb. 2021.

Tollis, Marc, et al. “Return to the Sea, Get Huge, Beat Cancer: An Analysis of Cetacean Genomes Including an Assembly for the Humpback Whale (Megaptera Novaeangliae).” Molecular Biology and Evolution, 9 May 2019.

我们通过发表论文来表彰学生 STEM 写作比赛的前 10 名获奖者。这是 Andrei Li 的作品。

2017 年，研究人员在吉萨大金字塔北面前架设了一个 μ 子望远镜。借用粒子物理学的一项技术，他们在金字塔内部发现了一个 100 英尺的“空洞”。

这篇来自多伦多 Monarch Park Collegiate 的 18 岁的 Andrei Li 撰写的文章是 The Learning Network 第四届年度 STEM 写作比赛的前 10 名获奖者之一，我们收到了 3,000 多份参赛作品。

Have you ever wanted to X-ray the pyramids? Peer into their bowels and search, à la Indiana Jones, for hidden chambers?

In the 1960s, a United States-Egypt joint archaeological expedition arrived at the pyramids of Giza with that exact goal. To accomplish this, they called upon an unexpected ally, a subatomic particle that had been discovered only three decades prior: the muon.

Leading this expedition was Luis Walter Alvarez, a physicist at the University of California Berkeley. In 1965, Dr. Alvarez thought of using muons to scour the insides of the Egyptian pyramids for hidden structures.

The muon is, in a sense, the electron’s larger sibling: Both have the same negative charge, but the muon is 207 times more massive. Born from the violent collisions between cosmic rays and atoms in the upper atmosphere, muons exist for a little over two microseconds before decaying into simpler particles.

Despite their short life spans, the highly energetic muons travel fast and far. Muons can “cross tens of meters of concrete. They’ll also pass through your body without doing anything,” explained Ralf Kaiser, a professor at the University of Glasgow. “They’re ubiquitous, penetrating and cost-free.”

For Dr. Alvarez, the muon’s abundance, safeness and penetrative properties made it the perfect candidate for peering inside the pyramids.

Dr. Alvarez and his team set up spark detectors around the Pyramid of Khafre. Dr. Alvarez’s spark detectors consisted of two metal plates with a small gap between them. Whenever a muon passed through the plates, it disturbed the gas molecules along its path and formed a visible spark across both plates. This allowed the researchers to extrapolate how many muons had passed through the pyramid from each direction.

In turn, they could deduce density differences inside the pyramid: Less dense regions, like hidden chambers, would let more muons through than denser regions, those completely filled with limestone.

What we see is “the shadows of the different parts,” said Giovanni Macedonio, who leads the Muon Radiography of Vesuvius project. He likened the process to X-ray imaging, which sees inside your body by projecting X-rays onto a film. The denser parts of your body, such as the bones, block more radiation and therefore appear as dark regions on the resulting image.

Dr. Alvarez presented his findings to the American Physical Society in 1969. Though no hidden chambers were detected in the Pyramid of Khafre, his work proved the viability of muon tomography, or muography, to the wider scientific community.

Subsequent technological advances, like the replacement of bulky spark chambers with compact plastic scintillators, catapulted muography into commonplace use. Muography has been applied in predicting volcanic eruptions and tracing illicit nuclear materials, and proposed in probing the tomb of China’s first emperor. Detectors now even fit into your pocket.

In a twist of fate, researchers announced the discovery of a hidden chamber within the Pyramid of Khufu in 2017. Had Dr. Alvarez not set up camp at the neighboring Pyramid of Khafre, he might have made this discovery himself.

Nonetheless, Dr. Alvarez’s work lit a spark for future scientists — and muons — to kindle.

Works Cited

Alvarez, Luis Walter, et al. “Search for Hidden Chambers in the Pyramids.” Science, 6 Feb. 1970.

Andrews, Robin George. “How Do You See Inside a Volcano? Try a Storm of Cosmic Particles.” The New York Times, 10 Nov. 2021.

Banino, Rob. “How Scientists Are Using Cosmic Radiation to Peek Inside the Pyramids.” BBC Science Focus Magazine, 10 June 2021.

Chen, Stephen. “Could Cosmic Rays Unlock the Secret Tomb Guarded by China’s Terracotta Army?” South China Morning Post, 15 Dec. 2021.

Chu, Jennifer. “Physicists Design $100 Handheld Muon Detector.” MIT News, 20 Nov. 2017.

Conover, Emily. “Muons Spill Secrets About Earth’s Hidden Structures.” Science News, 22 April 2022.

“DOE Explains … Muons.” U.S. Department of Energy.

Leone, Giovanni, et al. “Muography as a New Complementary Tool in Monitoring Volcanic Hazard: Implications for Early Warning Systems.” Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 10 Nov. 2021.

Morishima, Kunihiro, et al. “Discovery of a Big Void in Khufu’s Pyramid by Observation of Cosmic-Ray Muons.” Nature, 2 Nov. 2017.

“Spark Chamber.” Encyclopaedia Britannica.