A team of mathematicians and physicists has discovered how ice formations are shaped by external forces, such as water temperature. Its newly published research may offer another means for gauging factors that cause ice to melt.
“The shapes and patterning of ice are sensitive indicators of the environmental conditions at which it melted, allowing us to ‘read’ the shape to infer factors such as the ambient water temperature,” explains Leif Ristroph, an associate professor at New York University’s Courant Institute of Mathematical Sciences and one of the authors of the paper, which appears in the journal Physical Review Letters.
“Our work helps to understand how melting induces unusual flow patterns that in turn affect melting, which is one of the many complexities affecting the ice on our planet,” adds author Alexandra Zidovska, an associate professor in NYU’s Department of Physics.
The paper’s other authors were Scott Weady, an NYU graduate student, and Josh Tong, an undergraduate in NYU’s College of Arts and Science at the time of the study.
In NYU’s Applied Mathematics Laboratory and Center for Soft Matter Research, the researchers studied, through a series of experiments, the melting of ice in water and, in particular, how the water temperature affects the eventual shapes and patterning of ice. To do so, they created ultra-pure ice, which is free of bubbles and other impurities. The team recorded the melting of ice submerged into water tanks in a “cold room,” which is similar to a walk-in refrigerator whose temperature is controlled and varied.
“We focused on the cold temperatures — 0 to 10 degrees Celsius — at which ice in natural waters typically melts, and we found a surprising variety of shapes that formed,” says Ristroph, who directs the Applied Mathematics Laboratory.
Specifically, at very cold temperatures — those under about 5 degrees C — the pieces take on the shape of a spike or “pinnacle” pointing downward — similar to an icicle, but perfectly smooth (with no ripples). For temperatures above approximately 7 degrees C, the same basic shape forms, but upside down — a spike pointing upward. For in between temperatures, the ice has wavy and rippled patterns melted into its surface. Similar patterns, called “scallops,” are found on icebergs and other ice surfaces in nature.
These shape differences are due to changes in water flows, which are determined by their temperatures.
“Melting causes gradients in the temperature of the water near the ice, which causes the liquid at different places to have different densities,” explains Weady. “This generates flows due to gravity — with heavier liquid sinking and lighter fluid rising — and such flows along the surface lead to different rates of melting at different locations and thus changes in shape.”
“The strange bit of physics is that liquid water has a highly unusual dependence of density on temperature, in particular a maximum of density at about 4 degrees C,” he adds. “This ‘density anomaly’ makes water unique in comparison to other fluids.”
The research shows that this property is responsible for producing very different flows, depending on the precise value of the water temperature. The downward pinnacles at low temperatures are associated with upward flows, while the upward pinnacles have downward flows. The scalloped patterns form because upward flows very near the surface interact with downward flows further away, destabilizing into vortices that carve pits into the ice.
“Our findings help to explain some characteristic shapes of ice seen in nature, specifically the so-called pinnacle morphology of icebergs that consists of sharp spikes or spires and the so-called scallops that consist of wavy patterns of pits,” notes Ristroph.
“The bigger context for this work relates to the changing climate of the Earth and the increased rate of ice melting across our planet,” he continues. “It’s important to better understand the detailed physics and math of melting at smaller scales, since these are key components of larger-scale climate models.”
The research was supported by grants from the National Science Foundation (PHY-1554880, CBET-1805506, DMS-1646339).
Astronaut study reveals effects of space travel on human bones – Euronews
By Will Dunham
WASHINGTON – A study of bone loss in 17 astronauts who flew aboard the International Space Station is providing a fuller understanding of the effects of space travel on the human body and steps that can mitigate it, crucial knowledge ahead of potential ambitious future missions.
The research amassed new data on bone loss in astronauts caused by the microgravity conditions of space and the degree to which bone mineral density can be regained on Earth. It involved 14 male and three female astronauts, average age 47, whose missions ranged from four to seven months in space, with an average of about 5-1/2 months.
A year after returning to Earth, the astronauts on average exhibited 2.1% reduced bone mineral density at the tibia – one of the bones of the lower leg – and 1.3% reduced bone strength. Nine did not recover bone mineral density after the space flight, experiencing permanent loss.
“We know that astronauts lose bone on long-duration spaceflight. What’s novel about this study is that we followed astronauts for one year after their space travel to understand if and how bone recovers,” said University of Calgary professor Leigh Gabel, an exercise scientist who was the lead author of the research published this week in the journal Scientific Reports https://www.nature.com/articles/s41598-022-13461-1.
“Astronauts experienced significant bone loss during six-month spaceflights – loss that we would expect to see in older adults over two decades on Earth, and they only recovered about half of that loss after one year back on Earth,” Gabel said.
The bone loss occurs because bones that typically would be weight-bearing on Earth do not carry weight in space. Space agencies are going to need to improve countermeasures – exercise regimes and nutrition – to help prevent bone loss, Gabel said.
“During spaceflight, fine bone structures thin, and eventually some of the bone rods disconnect from one another. Once the astronaut comes back to Earth, the remaining bone connections can thicken and strengthen, but the ones that disconnected in space can’t be rebuilt, so the astronaut’s overall bone structure permanently changes,” Gabel said.
The study’s astronauts flew on the space station in the past seven years. The study did not give their nationalities but they were from the U.S. space agency NASA, Canadian Space Agency, European Space Agency and Japan Aerospace Exploration Agency.
Space travel poses various challenges to the human body – key concerns for space agencies as they plan new explorations. For instance, NASA is aiming to send astronauts back to the moon, a mission now planned for 2025 at the earliest. That could be a prelude to future astronaut missions to Mars or a longer-term presence on the lunar surface.
“Microgravity affects a lot of body systems, muscle and bone being among them,” Gabel said.
“The cardiovascular system also experiences many changes. Without gravity pulling blood towards our feet, astronauts experience a fluid shift that causes more blood to pool in the upper body. This can affect the cardiovascular system and vision.
“Radiation is also a large health concern for astronauts as the further they travel from Earth the greater exposure to the sun’s radiation and increased cancer risk,” Gabel said.
The study showed that longer space missions resulted both in more bone loss and a lower likelihood of recovering bone afterward. In-flight exercise – resistance training on the space station – proved important for preventing muscle and bone loss. Astronauts who performed more deadlifts compared to what they usually did on Earth were found to be more likely to recover bone after the mission.
“There is a lot we still do not know regarding how microgravity affects human health, particularly on space missions longer than six months, and on the long-term health consequences,” Gabel said. “We really hope that bone loss eventually plateaus on longer missions, that people will stop losing bone, but we don’t know.”
Understanding Plants Is Key to Finding a Cure for Cancer – SciTechDaily
If scientists can fully understand plant growth, they might be able to find a cancer cure
In order to increase agricultural yields, it is important to understand how plants process light. Plants use light to determine when to grow and bloom. Plants find light using proteins called photoreceptors. However, understanding plants have impacts in fields other than agriculture. Ullas Pedmale, an assistant professor at Cold Spring Harbor Laboratory (CSHL), and his colleagues have discovered how the proteins UBP12 and UBP13 regulate the activity of a CRY2 photoreceptor. Their finding could make new growth-control strategies apparent, with potential implications well beyond agriculture.
There are CRY photoreceptors in both plants and people. They are connected to a number of conditions including diabetes, cancer, and several brain disorders. CRY2 helps in regulating growth in both people and plants. Uncontrolled development in plants reduces their viability, whereas it causes cancer in humans. “If we understand growth,” Pedmale says, “we can cure cancer.”
Plants need the right amount of CRY2 to know when to grow and flower. Pedmale and former postdoctoral fellow Louise Lindbäck discovered that manipulating UBP12 and UBP13 can change the amount of CRY2 in plants. They found that increasing UBP12 and UBP13 reduces CRY2 levels. This made plants think there wasn’t enough light. In response, they grew longer, abnormal stems to reach more. Pedmale says:
“We have a way to understand growth here—and we could manipulate growth just by manipulating two proteins. We have found a way we can actually increase flower output. You need flowering for food. If there’s no flower, there is no grain, no rice, no wheat, no maize.”
Pedmale and Lindbäck didn’t know exactly how UBP12 and UBP13 regulated CRY2. When the researchers took a closer look, they made a surprising discovery. In humans and other organisms, versions of UBP12 and UBP13 protect CRY photoreceptors from degradation. But in plants, the team saw the opposite. UBP12 and UBP13 were actually helping degrade CRY2 instead. Lindbäck, who is currently a research and developmental engineer at Nordic Biomarker in Sweden, explains:
“From literature, it’s known that if you find an interaction like this, it will protect from degradation. Initially, we saw the opposite, and we thought, ‘okay, maybe I did something wrong,’ but then when I did it a few times, we realized, ‘okay, this is true.’ Instead of protecting CRY2, it causes CRY2 to degrade.”
Pedmale hopes their discovery will help plant researchers and plant breeders improve crop yields. He also hopes his work helps inform cancer research. “My colleagues at CSHL are working hard trying to understand cancer,” he says. “We are coming at it from a different angle with plants.”
The study was funded by the National Institutes of Health.
Reference: “UBP12 and UBP13 deubiquitinases destabilize the CRY2 blue light receptor to regulate Arabidopsis growth” by Louise N. Lindbäck, Yuzhao Hu, Amanda Ackermann, Oliver Artz and Ullas V. Pedmale, 13 June 2022, Current Biology.
Rocket Lab's Lunar Photon Completes Sixth Orbit Raise for NASA's CAPSTONE Mission to The Moon – Parabolic Arc – Parabolic Arc
LONG BEACH, Calif. (Rocket Lab PR) — Rocket Lab USA, Inc. (Nasdaq: RKLB) (“Rocket Lab” or “the Company”), a leading launch and space systems company, today confirmed its Photon Lunar spacecraft successfully completed a sixth on-orbit burn of the HyperCurie engine, bringing the CAPSTONE satellite closer to the Moon. Lunar Photon’s apogee – the point at which the spacecraft is farthest from Earth during its orbit – is now 43,297 miles (69,680 km).
This sixth burn was originally scheduled to be two burns, but Rocket Lab’s space systems team determined the HyperCurie engine would be capable of performing a single maneuver to accomplish the same delta-v, so combined the two.
The next and final burn is designed to set CAPSTONE on a ballistic lunar transfer trajectory to the Moon travelling at 24,500 mph (39,400 km/h) to break free of Earth’s orbit. This final maneuver is currently scheduled to take place as early as July 4th. After separating from Lunar Photon, CAPSTONE will use its own propulsion and the Sun’s gravity to navigate the rest of the way to the Moon, a four-month journey that will have CAPSTONE arriving to its lunar orbit on Nov. 13.
Designed and built Terran Orbital, and owned and operated by Advanced Space on behalf of NASA, the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) satellite will be the first spacecraft to test the Near Rectilinear Halo Orbit (NRHO) around the Moon. This is the same orbit intended for NASA’s Gateway, a multipurpose Moon-orbiting station that will provide essential support for long-term astronaut lunar missions as part of the Artemis program. CAPSTONE was successfully launched to space on Rocket Lab’s Electron launch vehicle on June 28.
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