Weizmann Institute

Tracking earth’s winds

A band of clouds above the equator, created by the rise of air within the Hadley cell and responsible for heavy rainfall in this region. (photo from Weizmann Institute)

Why do parts of earth become rainforests, whereas others turn into deserts? A new study exposes the far-reaching impact of human activity on a global airflow phenomenon that crucially affects earth’s regional climates.

In the tropics, above the equatorial rainforests and oceans, the strong solar radiation hitting earth propels a stream of warm, moist air far upward. Once reaching the upper atmosphere, this stream moves in both hemispheres toward the poles; it then descends in the subtropical regions at around 20 to 30 degrees latitude, contributing to the creation of massive deserts like the Sahara in northern Africa. From there, the stream – known as the Hadley cell – returns to the equator, where it heats up and rises again, embarking on its circular journey anew.

The two Hadley cells – the northern and the southern – circulate most of the heat and humidity across low latitudes, greatly affecting the global distribution of climate regions. When the warm, moist air rises, it cools down, allowing water vapour to condense, which leads to heavy rainfall deep in the tropics. In contrast, the streams of air that descend toward the earth in subtropical regions are accompanied by warm, dry winds that reduce rainfall. In essence, the Hadley cells determine which regions in the tropics and the subtropics will have arid deserts and which will be blessed with abundant rainfall. Israel is located on the margins of the northern Hadley cell, which contributes to the country’s semiarid climate.

Because of their huge significance, the Hadley cells are of great interest to climate scientists. However, while there is plenty of global data about rainfall and temperature, measuring airflow throughout the atmosphere is next to impossible. Adding to the quandary, the various models seeking to make sense of the Hadley cells have been found to contradict one another. Global climate models, which are used for climate projections, indicate that the northern Hadley cell has weakened over the past few decades, whereas observation-based analyses suggest the exact opposite.

An uncertainty over a system that is so essential to earth’s climate detracts from the researchers’ ability to assess how much humans have contributed to recent climate change. This, in turn, undermines the credibility of climate projections, making it ever harder to formulate policies required for dealing with the climate crisis. The latest report of the Intergovernmental Panel on Climate Change, the most important document in the field, makes a special point of this issue.

In a paper published in Nature, Dr. Rei Chemke, of the earth and planetary sciences department at the Weizmann Institute of Science, and Dr. Janni Yuval, of the Massachusetts Institute of Technology, address the uncertainty that has plagued the existing models for the past two decades. They propose an observation-based method for measuring the intensity of airflow in the Hadley cells.

To tackle the challenge, Chemke and Yuval looked for readily available data they could use to formulate a new way of measuring the cells’ intensity. After examining physics equations describing airflow, they identified a relationship between the Hadley cell intensity and a constantly monitored parameter: air pressure at sea level. They then examined observational data collected over several decades and reached the conclusion that the intensity of the northern Hadley cell has indeed been weakening – just as suggested by global climate models. Moreover, they were able to show, with more than 99% certainty, that this weakening has been the result of human activity and will likely continue.

What, then, is to be expected? Over the coming decades, the weakening of the northern Hadley cell is likely to mitigate the projected precipitation changes at low latitudes. It will act to temper both the increase of rainfall in equatorial regions and the reduction of rainfall in the subtropical regions. This tempering, however, might only reduce, but not overcome, the projected aridification and desertification of Israel.

“In our follow-up study,” said Chemke, “we will examine whether a similar weakening in the Hadley cell has happened in the past thousand years owing to natural phenomena – and that will allow us to assess how unprecedented these human-induced changes are.”

– Courtesy Weizmann Institute

Look on bright sides of earth

The southern and northern hemispheres look equally bright in this iconic image of earth, titled “The Blue Marble,” which the crew of the Apollo 17 spacecraft took on Dec. 7, 1972. (photo from NASA)

Why do earth’s hemispheres look equally bright when viewed from space? Weizmann Institute scientists offer an answer to this decades-old question.

When looking at the earth from space, its hemispheres – northern and southern – appear equally bright. This is unexpected because the southern hemisphere is mostly covered with dark oceans, whereas the northern hemisphere has a vast land area that is much brighter than these oceans. For years, the brightness symmetry between hemispheres remained a mystery. In a new study, published in the Proceedings of the National Academy of Sciences (PNAS), Weizmann Institute of Science researchers and their collaborators reveal a strong correlation between storm intensity, cloudiness and the solar energy reflection rate in each hemisphere. They offer a solution to the mystery, alongside an assessment of how climate change might alter the reflection rate in the future.

As early as the 1970s, when scientists analyzed data from the first meteorological satellites, they were surprised to find out that the two hemispheres reflect the same amount of solar radiation. Reflectivity of solar radiation is known in scientific lingo as “albedo.” To better comprehend what albedo is, think about driving at night: it is easy to spot the intermittent white lines, which reflect light from the car’s headlights well, but difficult to discern the dark asphalt. The same is true when observing earth from space: the ratio of the solar energy hitting the earth to the energy reflected by each region is determined by various factors. One of them is the ratio of dark oceans to bright land, which differ in reflectivity, just like asphalt and intermittent white lines. The land area of the northern hemisphere is about twice as large as that of the southern and, indeed, when measuring near the surface of the earth, when the skies are clear, there is more than a 10% difference in albedo. Still, both hemispheres appear to be equally bright from space.

In this study, the team of researchers, led by Prof. Yohai Kaspi and Or Hadas of Weizmann’s earth and planetary sciences department, focused on another factor influencing albedo, one located in high altitudes and reflecting solar radiation – clouds. The team analyzed data derived from the world’s most advanced databases, including cloud data collected via NASA satellites (CERES), as well as data from ERA5, which is a global weather database containing information collected using a variety of sources in the air and on the ground, dating back to 1950. ERA5 data was used to complete cloud data and to cross-correlate 50 years of this data with information on the intensity of cyclones and anticyclones.

photo - Prof. Yohai Kaspi, left, and Or Hadas of the Weizmann Institute of Science — Prof. Yohai Kaspi, left, and Or Hadas of the Weizmann Institute of Science. (photo from Weizmann Institute)

Next, the scientists classified storms of the last 50 years into three categories, according to intensity. They discovered a direct link between storm intensity and the number of clouds forming around the storm. While northern hemisphere and land areas in general are characterized by weaker storms, above oceans in the southern hemisphere, moderate and strong storms prevail. Data analysis showed that the link between storm intensity and cloudiness accounts for the difference in cloudiness between the hemispheres.

“Cloud albedo arising from strong storms above the southern hemisphere was found to be a high-precision offsetting agent to the large land area in the northern hemisphere, and thus symmetry is preserved,” said Hadas, adding: “This suggests that storms are the linking factor between the brightness of earth’s surface and that of clouds, solving the symmetry mystery.”

Will climate change have an impact?

Earth has been undergoing rapid change in recent years, owing to climate change. To examine whether and how this could affect hemispheric albedo symmetry, the scientists used CMIP6, a set of models run by climate modeling centres around the world to simulate climate change. One of these models’ major shortcomings is their limited ability to predict the degree of cloudiness. Nevertheless, the relation found in this study between storm intensity and cloudiness enables scientists to assess future cloud amounts, based on storm predictions.

Models predict global warming will result in a decreased frequency of all storms above the northern hemisphere and of weak and moderate storms above the southern hemisphere. However, the strongest storms of the southern hemisphere will intensify. The cause of these predicted differences is “Arctic amplification,” a phenomenon in which the North Pole warms twice as fast as earth’s mean warming rate. One might speculate that this difference should break hemispheric albedo symmetry. However, the research shows that a further increase in storm intensity might not change the degree of cloudiness in the southern hemisphere because cloud amounts reach saturation in very strong storms. Thus, symmetry might be preserved.

“It is not yet possible to determine with certainty whether the symmetry will break in the face of global warming,” said Kaspi. “However, the new research solves a basic scientific question and deepens our understanding of earth’s radiation balance and its effectors. As global warming continues, geoengineered solutions will become vital for human life to carry on alongside it. I hope that a better understanding of basic climate phenomena, such as the hemispheric albedo symmetry, will help in developing these solutions.”

Other collaborators in conducting this study include Dr. George Datseris and Prof. Bjorn Stevens of Max Planck Institute for Meteorology, Germany; Dr. Joaquin Blanco and Prof. Rodrigo Caballero of Stockholm University, Sweden; and Dr. Sandrine Bony of Sorbonne University, France. Kaspi is head of the Helen Kimmel Centre for Planetary Science; his research is supported by the Yotam Project and Rene Braginsky.

– Courtesy Weizmann Institute

Studying social sense

Michael Gliksberg, left, and Prof. Gil Levkowitz are among the researchers who have discovered that oxytocin in a developing zebrafish brain determines later social behaviour. (photo from Weizmann Institute)

Whenever we decide to throw a party, invite in-laws to dinner or embark on a cruise, we are driven by the most basic component of social behaviour: the desire to hang out with other humans. Considering that the drive to form groups with members of one’s own species has been conserved throughout evolution, it’s evident that social behaviour is governed by genes, at least to some degree. But our parents and teachers help us hone our social graces, so teasing apart the effects of nature and nurture on this behaviour is hard, if not impossible. By studying zebrafish, Weizmann Institute of Science researchers, in collaboration with scientists in Portugal, have managed to solve part of the riddle of how social behaviour is hardwired into the developing brain.

Zebrafish are perfect for studying the inborn basis of behaviour because they receive zero nurturing from parents. “Some fish species take care of their young, but not zebrafish,” explained Prof. Gil Levkowitz of the Weizmann Institute’s molecular cell biology and molecular neuroscience departments, who headed the research team together with Prof. Rui F. Oliveira of Instituto Gulbenkian de Ciência in Portugal. “The female zebrafish spawns several hundred eggs, which are fertilized by sperm released into the water by the male. She does provide her offspring with a ‘lunchbox’ – a protein sac, or yolk, that makes up part of the egg – but, otherwise, her message to her children is: manage on your own.”

At about four weeks of age, the centimetre-long juvenile fish, just out of the larval stage, begin to socialize. Though not as exquisitely synchronized as the schools of moonfish in the movie Finding Nemo, they do exhibit a strong tendency to swim together as a group, termed a shoal. Much like humans, they have an incentive to seek company; in their case, the group provides them with advantages in searching for food, overcoming currents, avoiding predators and finding mates. The shoaling behaviour of zebrafish requires sophisticated processing of visual and social cues, very similar to that which takes place in the brains of socializing humans. In particular, the zebrafish must be able to identify other fish as belonging to their own, “friendly” – as opposed to different or, worse yet, predatory – species.

To learn how the social behaviour of zebrafish develops, the researchers focused on the hormone oxytocin, one of the most important neurochemicals known to enhance social interactions, including bonding. Postdoctoral fellow Dr. Ana Rita Nunes and doctoral student Michael Gliksberg created a system for exploring the effects of oxytocin on the developing brains of zebrafish larvae. They produced transgenic larvae whose oxytocin-making neurons harboured a bacterial gene encoding fatal sensitivity to antibiotics. The researchers could then eliminate these neurons from the brains of the larvae at different stages of their development by adding antibiotics to the water, and they later observed the zebrafish behaviour as they became adults.

The scientists discovered that the larvae whose brains lacked oxytocin early on – specifically, in the first two weeks of life – grew into adult fish with an impaired capacity for social interaction, namely, swimming in a shoal. Although their brains regenerated the oxytocin neurons later in life, this capacity was not restored. This meant that, for adults to be capable of social behaviour, their brains had to be organized by oxytocin in a certain manner during a critical time window of brain development in which the social traits are established.

The researchers further discovered the mechanisms by which oxytocin primes the growing brain for socializing. They showed that oxytocin-producing neurons were critical to the birth of another type of neuron, one that releases the neurotransmitter dopamine, which is known to regulate feelings of reward and motivation. Zebrafish whose brains had not been exposed to oxytocin during the first two weeks of life had reduced numbers of dopamine-making neurons, as well as a reduced number of connections to these neurons, in two distinct brain areas.

One of these areas was responsible for processing visual stimuli, apparently of the kind essential for recognizing potential swimming partners. An analogous area in the brains of mammals, including humans, is involved in processing visual cues in social situations. It controls eye movements that scan, for example, different elements of the face in a particular order to decipher facial expressions. This pattern is often absent in people with autism, suggesting that their brains respond to social-based visual cues differently.

The other dopamine-deficient brain area in the zebrafish was analogous to a major reward centre in the mammalian brain, which is involved in the positive reinforcement of social interactions.

A lack of oxytocin in the critical early developmental period also disrupted a system of neuronal connections known as the social decision-making network – a group of brain areas that work together to process social information. In fish whose brains had developed without oxytocin, the synchronization patterns of neuronal activities among these centres were completely different from those of regular fish.

Nunes summarized: “Oxytocin organizes the developing brain in a way that’s essential for responding to social situations.”

– Courtesy Weizmann Institute

Community milestones … Goldschmidt, Mines, BGU & Weizmann Institute

A German translation of the Talmud, and the first translation of the book ever completed by a single person, is now available on Sefaria, a free nonprofit online library of Jewish texts. The translation by scholar Lazarus Goldschmidt was the first German translation of the Talmud and was released in 1935. While it is used in German Jewish studies departments and universities, it had not been widely accessible to the general public until now.

screenshot - Penny Goldsmith — *(screenshot)*

A celebration of the release took place virtually on Oct. 24. One of the speakers was Penny Goldsmith, Goldschmidt’s eldest granddaughter. Goldsmith is a longtime anti-poverty community worker in Vancouver, and owns a small independent publishing company, Lazara Press, named after her grandfather, who died a few months before she was born. She spoke of her grandfather’s books, “beautiful typographical masterpieces.”

“Grandfather was a type and book designer,” she said. Among his books were literature and poetry, including a collection of poetry he wrote in his early 20s, in Hebrew, “a very unusual choice,” Goldsmith noted, “as Hebrew at that time was reserved for religious study only.”

Goldschmidt was a scholar of Near Eastern languages and, in addition to the Talmud, he translated other religious texts, including a Hebrew translation of the Ethiopic Book of Enoch and a German translation of the Koran. Born in Lithuania, he learned German at the age of 18. His translation of the Talmud took 39 years to complete and he continued to make revisions after publication. He was also a collector of rare books and his extensive collection is now part of the Royal Library in Copenhagen.

After the Goldschmidt Talmud translation became public domain in January 2021, a team of four led by Igor Itkin, a rabbinical student at Rabbinerseminar zu Berlin, integrated its 9,434 pages of text into Sefaria’s free online library. The team’s work included manually linking sections of the translation to corresponding Talmud texts in English and Hebrew/Aramaic already in the Sefaria library. The connections allow scholars, educators and others to navigate between the translations and connect them to the larger library of Jewish scholarship. The team’s work was supported by a grant from the Rothschild Foundation Hanadiv Europe.

***

The Rivals and Other Stories by Jonah Rosenfeld, translated from the Yiddish by Vancouver’s Rachel Mines – who recently retired from Langara College’s English department – has been selected by the Yiddish Book Centre as one of its picks for the 2022 Great Jewish Books Club. The book is available through the Yiddish Book Centre’s store and other online booksellers, including its publisher, Syracuse University Press, which is offering The Rivals at a 50% discount until Dec 1, 2021 (press.syr.edu).

Rosenfeld was a prolific and popular writer from the early 1900s until his death in 1944. Although his writing received critical praise, very little was translated into English until the publication of The Rivals. His stories foreground social anxiety, cultural dislocation, family dysfunction and the search for meaningful relationships – themes just as relevant today as they were to their original audiences. (See jewishindependent.ca/stories-that-explore-the-mind.)

***

photo - The National Autism Research Centre of Israel — The National Autism Research Centre of Israel *(photo from Canadian Associates of Ben-Gurion University of the Negev)*

The Azrieli Foundation recently donated $15.6 million Cdn to the National Autism Research Centre of Israel, a collaboration between scientists from Ben-Gurion University of the Negev and clinicians from Soroka University Medical Centre (SUMC), both in the city of Be’er Sheva, Israel. The centre, originally established by the Ministry of Science and Technology, is dedicated to translational research that aims to revolutionize diagnosis techniques and interventions for autism and other neurodevelopmental conditions. In honour of the donation, the centre has been renamed the Azrieli National Centre for Autism and Neurodevelopment Research.

A dedicated facility inside SUMC will be constructed that will double the space for working with children with autism spectrum disorder and performing research. It will house genetics/bioinformatics, biomarker-detection and neuroimaging labs. Existing data collection will be expanded to many autism clinics throughout Israel, where multiple types of clinical and behavioural data, biological samples (e.g., DNA and blood samples) and neuroimaging data will be collected. This data collection will enable the rapid expansion of the National Autism Database, which will triple in size within five years. New faculty members, post-docs and graduate students, as well as scientific, clinical, technical and administrative support staff will be recruited to manage the data collection and sharing effort.

***

photo - Naomi Azrieli, chief executive officer, Azrieli Foundation Canada, and co-chair, Azrieli Foundation Israel, at the Nov. 7 announcement in Montreal, which took place concurrently with the announcement in Israel — Naomi Azrieli, chief executive officer, Azrieli Foundation Canada, and co-chair, Azrieli Foundation Israel, at the Nov. 7 announcement in Montreal, which took place concurrently with the announcement in Israel. *(photo by PBL Photography)*

The Weizmann Institute of Science and Weizmann Canada recently received a donation of $50 million US from the Azrieli Foundation, to enable catalytic brain research with the establishment of the Azrieli Institute for Brain and Neural Sciences. A longstanding supporter of the institute, this latest donation adds to past philanthropic investments of nearly $30 million US by the foundation towards Weizmann research facilities and fellowships.

Weizmann’s Azrieli Institute for Brain and Neural Sciences, which will be located at the Weizmann Institute campus in Rehovot, Israel, will promote the full spectrum of neuroscience research, from basic, curiosity-driven studies to translational work of high clinical relevance, with global impact. The donation will enable the construction of a new building that will serve as a hub for neuroscience activities, facilities and technologies.

The Azrieli Institute will focus on research in the development of neural networks; perception and action; mental and emotional health, positive neuroscience; learning, memory and cognition; the aging brain; neurodegeneration; injury and regeneration; theoretical and computational neuroscience; development of innovative neurotechnologies; and integrative brain disorders.

Studying the “love hormone”

Oxytocin, a peptide produced in the brain, may bring hearts together – or it can help induce aggression. (image from Weizmann Institute)

During the pandemic lockdown, as couples have been forced to spend days and weeks in each other’s company, some have found their love renewed while others are on their way to divorce court. Oxytocin, a peptide produced in the brain, is complicated in that way: a neuromodulator, it may bring hearts together or it can help induce aggression. This conclusion arises from research led by Weizmann Institute of Science researchers in which mice living in semi-natural conditions had their oxytocin-producing brain cells manipulated in a precise manner. The findings, which were published in Neuron, could shed new light on efforts to use oxytocin to treat a variety of psychiatric conditions, from social anxiety and autism to schizophrenia.

Much of what we know about the actions of neuromodulators like oxytocin comes from behavioural studies of lab animals in standard lab conditions. These conditions are strictly controlled and artificial, in part so that researchers can limit the number of variables affecting behaviour. But a number of recent studies suggest that the actions of a mouse in a semi-natural environment can teach us much more about natural behaviour, especially when we mean to apply those findings to humans.

Prof. Alon Chen’s lab group in the institute’s neurobiology department have created an experimental setup that enables them to observe mice in something approaching their natural living conditions – an environment enriched with stimuli they can explore – and their activity is monitored day and night with cameras and analyzed computationally. The present study, which has been ongoing for the past eight years, was led by research students Sergey Anpilov and Noa Eren, and staff scientist Dr. Yair Shemesh in Chen’s lab group.

The innovation in this experiment was to incorporate optogenetics – a method that enables researchers to turn specific neurons in the brain on or off using light. To create an optogenetic setup that would enable the team to study mice that were behaving naturally, the group developed a compact, lightweight, wireless device with which the scientists could activate nerve cells by remote control. With the help of optogenetics expert Prof. Ofer Yizhar of the same department, the group introduced a protein previously developed by Yizhar into the oxytocin-producing brain cells in the mice. When light from the wireless device touched those neurons, they became more sensitized to input from the other brain cells in their network.

“Our first goal,” said Anpilov, “was to reach that ‘sweet spot’ of experimental setups in which we track behaviour in a natural environment, without relinquishing the ability to ask pointed scientific questions about brain functions.”

Shemesh added that “the classical experimental setup is not only lacking in stimuli, the measurements tend to span mere minutes, while we had the capacity to track social dynamics in a group over the course of days.”

Delving into the role of oxytocin was sort of a test drive for the experimental system. It had been believed that this hormone mediates pro-social behaviour. But findings have been conflicting, and some have proposed another hypothesis, termed “social salience,” stating that oxytocin might be involved in amplifying the perception of diverse social cues, which could then result in pro-social or antagonistic behaviours, depending on such factors as individual character and the environment.

To test the social salience hypothesis, the team used mice in which they could gently activate the oxytocin-producing cells in the hypothalamus, placing them first in the enriched, semi-natural lab environments. To compare, they repeated the experiment with mice placed in the standard, sterile lab setups.

In the semi-natural environment, the mice at first displayed heightened interest in one another, but this was soon accompanied by a rise in aggressive behaviour. In contrast, increasing oxytocin production in the mice in classical lab conditions resulted in reduced aggression.

“In an all-male, natural social setting, we would expect to see belligerent behaviour as they compete for territory or food,” said Anpilov. “That is, the social conditions are conducive to competition and aggression. In the standard lab setup, a different social situation leads to a different effect for the oxytocin.”

If the “love hormone” is more likely a “social hormone,” what does that mean for its pharmaceutical applications?

“Oxytocin is involved, as previous experiments have shown, in such social behaviours as making eye contact or feelings of closeness,” said Eren, “but our work shows it does not improve sociability across the board. Its effects depend on both context and personality.”

This implies that, if oxytocin is to be used therapeutically, a much more nuanced view is needed in research: “If we want to understand the complexities of behaviour, we need to study behaviour in a complex environment. Only then can we begin to translate our findings to human behaviour,” she said.

Participating in this research were scientists at the Max Planck Institute for Psychiatry in Munich, including research students Asaf Benjamin and Stoyo Karamihalev, staff scientist Dr. Julien Dine and postdoctoral fellow Dr. Oren Forkosh of the Chen lab; Prof. Shlomo Wagner and postdoctoral fellow Dr. Hala Harony-Nicolas of Haifa University; Prof. Inga Neumann and research student Vinicius Oliveira of Regensburg University, Germany; and electrical engineer Avi Dagan.

Cassini’s view of Saturn

Saturn’s main rings, along with its moons, are much brighter than most stars. As a result, much shorter exposure times (10 milliseconds, in this case) are required to produce an image and not saturate the detectors of the imaging cameras on Cassini. A longer exposure would be required to capture the stars as well. (photo from NASA/JPL-Caltech/Space Science Institute)

Grand Finale was the official name of Cassini’s last act: a risky orbit between Saturn’s rings and atmosphere in an attempt to explore the planet up close, right before the craft went up in flames.

Prof. Yohai Kaspi and Dr. Eli Galanti of the Weizmann Institute’s earth and planetary sciences department led one of the studies on Cassini’s final mission, revealing the depth of Saturn’s jet streams – the strongest measured in the solar system, with winds of up to 1,500 kilometres per hour – and found them to reach a depth of around 9,000 kilometres. Teaming up with research partners in Italy and the United States, their study also helped reveal the age of the planet’s rings. The findings of these studies were published this month in Science.

Cassini was one of the more successful planetary missions, orbiting and returning information on Saturn and its moons for the last 20 years. As the mission was approaching its end, it was decided to end its life with a non-circular orbit swinging in very close to the planet, followed by a final plunge into the gaseous mass. Kaspi and Galanti joined the Cassini team following their work as part of NASA’s Juno science team, which had employed a similar orbit to produce the most reliable measurements yet of Jupiter’s atmospheric depth. The Cassini scientists thought it would be possible to do the same for Saturn, and the Weizmann scientists were called in to apply their methodology to the Saturn measurements.

Kaspi described the challenge: “We detect small variations in the gravity field as the craft orbits Saturn, and translate these into the atmospheric wind that produces them. There was no guarantee it would work for Saturn, as the gravity signal on Saturn is more difficult to interpret than what we had on Jupiter. We discovered that not only did it work for both planets, but that same physical processes control the depth of the flows on these two planets.”

To calculate the depth of the winds, the gravity measurements undertaken by Cassini were analyzed with the theoretical model developed by the Weizmann researchers. “We also teamed up with a second group investigating the internal structure of the planet,” said Galanti. “Together, we calculated that the depth of the atmosphere is up to around 9,000 kilometres. That is three times deeper than that of Jupiter. We also found that, just as on Jupiter, a strong internal magnetic field is what limits the depth of this layer of the atmosphere. Our theory worked twice, which provides strong support for its validity.”

In the same study, the researchers analyzed the Grand Finale data from Saturn’s rings, finding they are at most 100 million years old. That is quite recent in the 4.5-billion-year history of the solar system. The planet in the night sky at the time of the first dinosaurs was, apparently, without the rings we know today.

For more on the research being conducted at the Weizmann Institute, visit wis-wander.weizmann.ac.il.

– Weizmann Institute

Saturn losing its rings

New NASA research confirms that Saturn is losing its iconic rings at the maximum rate estimated from Voyager 1 and 2 observations made decades ago. The rings are being pulled into Saturn by gravity as a dusty rain of ice particles under the influence of Saturn’s magnetic field.

photo - Saturn’s northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Since NASA’s Cassini spacecraft arrived at Saturn in mid-2004, the shifting angle of sunlight as the seasons march forward has illuminated the giant hexagon-shaped jet stream around the north polar region, and the subtle bluish hues seen earlier in the mission have continued to fade — Saturn’s northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Since NASA’s Cassini spacecraft arrived at Saturn in mid-2004, the shifting angle of sunlight as the seasons march forward has illuminated the giant hexagon-shaped jet stream around the north polar region, and the subtle bluish hues seen earlier in the mission have continued to fade. *(photo from NASA/JPL-Caltech/Space Science Institute)*

“We estimate that this ‘ring rain’ drains an amount of water products that could fill an Olympic-sized swimming pool from Saturn’s rings in half an hour,” said James O’Donoghue of NASA’s Goddard Space Flight Centre in Greenbelt, Md. “From this alone, the entire ring system will be gone in 300 million years, but add to this the Cassini-spacecraft measured ring-material detected falling into Saturn’s equator, and the rings have less than 100 million years to live. This is relatively short, compared to Saturn’s age of over four billion years.” O’Donoghue is lead author of a study on Saturn’s ring rain appearing in Icarus Dec. 17.

Scientists have long wondered if Saturn was formed with the rings or if the planet acquired them later in life. The new research favours the latter scenario, indicating that they are unlikely to be older than 100 million years, as it would take that long for the C-ring to become what it is today assuming it was once as dense as the B-ring. “We are lucky to be around to see Saturn’s ring system, which appears to be in the middle of its lifetime. However, if rings are temporary, perhaps we just missed out on seeing giant ring systems of Jupiter, Uranus and Neptune, which have only thin ringlets today,” O’Donoghue added.

Various theories have been proposed for the ring’s origin. If the planet got them later in life, the rings could have formed when small, icy moons in orbit around Saturn collided, perhaps because their orbits were perturbed by a gravitational tug from a passing asteroid or comet.

– NASA Goddard Space Flight Centre

Too much food wasted

Millions more could be fed by the same resources if our diets changed. (photo from wis-wander.weizmann.ac.il)

About a third of the food produced for human consumption is estimated to be lost or wasted globally. But the biggest waste, which is not even included in this estimate, may be through dietary choices that result in the squandering of environmental resources. In a study published in the Proceedings of the National Academy of Sciences of the United States of America, researchers at the Weizmann Institute of Science in Rehovot, Israel, and their colleagues have found a novel way to define and quantify this second type of wastage. The scientists have called it “opportunity food loss,” a term inspired by the “opportunity cost” concept in economics, which refers to the cost of choosing a particular alternative over better options.

Opportunity food loss stems from using agricultural land to produce animal-based food instead of nutritionally comparable plant-based alternatives. The researchers report that, in the United States alone, avoiding opportunity food loss – that is, replacing all animal-based items with edible crops for human consumption – would add enough food to feed 350 million additional people, or more than the total U.S. population, with the same land resources.

“Our analysis has shown that favouring a plant-based diet can potentially yield more food than eliminating all the conventionally defined causes of food loss,” said lead author Dr. Alon Shepon, who worked in the lab of Prof. Ron Milo in the plant and environmental sciences department. The Weizmann researchers collaborated with Prof. Gidon Eshel of Bard College and Dr. Elad Noor of ETZ Zürich.

The scientists compared the resources needed to produce five major categories of animal-based food – beef, pork, dairy, poultry and eggs – with the resources required to grow edible crops of similar nutritional value in terms of protein, calories and micronutrients. They found that plant-based replacements could produce two- to 20-fold more protein per acre.

The most dramatic results were obtained for beef. The researchers compared it with a mix of crops – soya, potatoes, cane sugar, peanuts and garlic – that deliver a similar nutritional profile when taken together in the right proportions. The land area that could produce 100 grams of protein from these crops would yield only four grams of edible protein from beef. In other words, using agricultural land for producing beef instead of replacement crops results in an opportunity food loss of 96 grams – that is, a loss of 96% – per unit of land. This means that the potential gain from diverting agricultural land from beef to plant-based foods for human consumption would be enormous.

The estimated losses from failing to replace other animal-based foods with nutritionally similar crops were also huge: 90% for pork, 75% for dairy, 50% for poultry and 40% for eggs – higher than all conventional food losses combined.

“Opportunity food loss must be taken into account if we want to make dietary choices enhancing global food security,” said Milo.

Milo’s research is supported by the Mary and Tom Beck Canadian Centre for Alternative Energy Research, which he heads; the Zuckerman STEM Leadership Program; Dana and Yossie Hollander; and the Larson Charitable Foundation. Milo is the incumbent of the Charles and Louise Gartner Professorial Chair.

For more on the research being conducted at the Weizmann Institute, visit wis-wander.weizmann.ac.il.

Getting closer look at Jupiter

This JunoCam image highlights Oval BA. (photo from nasa.gov)

The U.S. National Aeronautics and Space Administration (NASA) recently released the first findings of the Juno research spacecraft, which entered Jupiter’s atmosphere last year.

The Weizmann Institute of Science’s Dr. Yohai Kaspi is a senior member of the Juno mission team. The reason why this research is so important, he said, is because it will allow us to better understand how the solar system was formed.

“To do that, we really need to understand Jupiter and how it was formed because, then, we can understand earth, in sequence,” said Kaspi.

photo - Dr. Yohai Kaspi of the Weizmann Institute of Science — Dr. Yohai Kaspi of the Weizmann Institute of Science. *(photo from WIS)*

For Kaspi, the fascination with space came at the early age of 7, when his dad shared some pictures of the Voyager I and II and took him stargazing. His interest grew from there, including when he was navigating in the Negev while in the Israel Defence Forces.

“My hobby growing up was competitive sailing,” said Kaspi. “That drew my interest into meteorology and understanding why the wind blows the way it does. Growing up in Nahariya, which borders Lebanon … all kinds of stuff [are] coming from Lebanon – currents, trash. It was very obvious where the wind or current was coming from and that connected to sailing.”

Kaspi studied math and physics at Hebrew University before heading to the United States, seeking adventure and a doctorate at Massachusetts Institute of Technology. Soon after, he was recruited to be a professor at the Weizmann Institute of Science.

While at MIT, Kaspi became connected to the Juno mission, developing instruments to help measure atmospheric conditions on Jupiter.

“I was interested in space and the weather,” said Kaspi. “I studied meteorology, as it kind of brings them together … [with] planetary science. We have planets, which resemble earth in some aspects, but we don’t understand their features and circulation.”

While Jupiter is by far the biggest planet in the solar system (11 times the diameter of earth) and has the greatest mass (300 times that of earth), it is a gas planet (i.e. it has no liquid or solid parts). Kaspi has studied Jupiter’s different weather zones and deltas.

“I developed a theory for understanding how deeply they extend,” said Kaspi. “When you look at Jupiter, you have this red and white belt, or zone. That’s all at the cloud level, so it condensates at the same temperature. But, we have no information what’s happening underneath them. What we needed was a global way to survey what was happening underneath the cloud layer. And that’s exactly what Juno is.

“During my PhD, I developed a new method to relate between the gravity field of the planet and the flows underneath this cloud layer. To understand Jupiter, we need to understand what’s happening in its interior.”

Kaspi has been involved with Juno since 2008, along with 30 to 40 other scientists who form the core of the mission, developing and designing the experiments, and interpreting the data.

photo - This enhanced colour view of Jupiter’s south pole was created by citizen scientist Gabriel Fiset using data from the JunoCam on NASA’s Juno spacecraft — This enhanced colour view of Jupiter’s south pole was created by citizen scientist Gabriel Fiset using data from the JunoCam on NASA’s Juno spacecraft. *(photo from nasa.gov)*

“We’re trying to deduce the depths of the flows from the gravity measurements of the planet,” explained Kaspi. “The purpose is to see what’s happening inside the planet. It has nine instruments and each one probes in different ways what is happening in the planet’s interior.

“One is a gravity instrument…. We send a beam from the spacecraft to earth. The beam travels 800 million kilometres and reaches earth. A desert in California captures that beam.

“We try to see the accelerations and decelerations of the spacecraft around the planet … trying to understand … the flow field and the gravity field of Jupiter.”

It was only when we first saw earth from space that we were able to understand the changing atmospheric conditions that are part of what is largely considered part of climate change, said Kaspi.

“We’d be able to understand how the solar system was formed, including earth,” he said of one of the project’s possible results. “For example, it’s really important for us to know if there’s a core inside Jupiter. A planet with a big or small core would have a different effect on the gravity field. When we measure the gravity field, we can deduce what’s happening deep inside the planet, which would lead us to different theories of how the solar system was formed.

“The connection to earth is we see the objects of Jupiter’s atmospheres … we don’t understand their strengths, how wide they are and how deep they are. We don’t have theories for that. If you want to have a good understanding of objects on earth, you have to look at the sister planet.”

The data-collecting portion of the Juno mission will come to a close at the end of this year. After 10 years of research and six orbits, the data will be analyzed to determine the direction of the mission going forward.

“We have already a lot of good data and we’re reaching a point where we can have significant results for understanding the structure, depths and composition of the atmosphere, but it’s a process,” said Kaspi. “Basically, we have one measurement every 53 days. So, every 53 days, I get my stuff and go to the U.S. and stay there for a week, analyzing the data and analyzing it for the rest of the 45 days, and then go back.”

Regardless of the results, Kaspi will continue the work he is doing at the Weizmann Institute on climate change and working on an instrument that will be sent to Jupiter on board the 2022 spacecraft being built by the European Space Agency.

“It will be the first Israeli instrument that will go beyond earth’s orbit,” said Kaspi. “That’s exciting. So, we’re involved in that and a variety of projects, trying to achieve fundamental understanding.”

As far as space exploration for the purpose of finding another planet fit for human dwelling, Kaspi said, “I’m just going to say that, if there is life in the solar system, it might be in the moons of Jupiter … because they have liquid water, a deep ocean, tens to hundreds of kilometres deep. Maybe there is life there.”

The public can follow the Juno mission on Facebook at facebook.com/nasajuno.

Rebeca Kuropatwa is a Winnipeg freelance writer.

Israel’s BDS website

Featured on israelbds.org are popular articles that describe the history of Israeli-international scientific cooperation, research that has resulted from that cooperation and the people involved, as well as links to scientific papers. (image from israelbds.org)

Building Dialogue through Science, or BDS, is the purpose of a new website, israelbds.org, which features the many and varied scientific studies that rely on close collaboration between Israeli researchers and those in different countries.

These studies range from the SESAME synchrotron, a Middle Eastern facility based in Jordan that serves life-sciences researchers from Egypt to Iran; efforts to discover the processes that lead to the stellar explosions known as supernovae, in which Israeli researchers are alerted to possible events in the California night sky; brain research; quantum physics studies; scientific archeology; and much more.

Featured on the website are popular articles that describe the history of Israeli-international scientific cooperation, research that has resulted from that cooperation and the people involved, as well as links to scientific papers.

“Building dialogue through science, rather than building walls, has always been our way of doing things,” said Weizmann Institute of Science president Prof. Daniel Zajfman. “If we are going to work against the other BDS [boycott, divest from and sanction Israel], we must do so with real information. That is the intent of the site we have created. When scientists cooperate in their research, they bring back to their countries an understanding of the ways people can work together on many levels – over and above the scientific – including respect for other cultures and a desire for peaceful coexistence. That is why we believe that cooperation between Israeli scientists and those in universities and research institutes around the globe must be preserved at all costs.”

The hope, indeed, is that anyone visiting the website will understand what the world stands to lose from cutting off ties to Israel’s researchers and preventing students and labs around the globe from benefiting from Israeli advances.

Valeria Ulisse, an Italian research student studying the development of the nervous system at the Weizmann Institute of Science sums it up: “In Italy, I was in a really good lab but I was missing something internally. I wanted to improve my knowledge, to start a new project, to change my life and I found the place to do it.”

Israeli science is open to collaboration with anyone, independent of their political opinions.

“Research thrives on the meeting of different worldviews, and it is important to preserve that freedom to meet and discuss, even with those with whom we don’t always agree,” said Zajfman.

An artificial odour test

(image from wis-wander.weizmann.ac.il)

Say someone claims to have developed a system to “capture” any odour in the form of a digital code – one that could be transmitted online or uploaded to the internet and faithfully reproduced at the receiving end. How could we be sure that the system is valid? In other words, how can we know that, for any possible odour someone has captured digitally and transmitted, the smell we receive is indeed a recognizable, fair rendition of the original?

Prof. David Harel of the Weizmann Institute of Science’s computer science and applied mathematics department explains that, as opposed to video and audio, an odour reproduction system is still far from viable, although some of the components already exist.

“We still don’t understand the process by which the numerous combinations of odourants in our environment are identified and sensed as a particular smell in our brains after they enter our noses, attach to the several hundred kinds of odour receptors there and are transferred to the brain as signals,” he said. But he and his colleagues had, already 15 years ago, laid out the basic principles of such a digital smell system.

This system would need a “sniffer” – a sort of artificial nose – to take “snapshots” of the odourous substances in the air. It would also need a “whiffer” that, something like a colour printer, would be able to mix a fixed set of around 50 chemical odourants in precisely given proportions – something in the way a printer mixes a small number of inks – and release measured amounts of the resulting odour into the air accurately, in a controlled manner.

photo - Prof. David Harel of the Weizmann Institute of Science — Prof. David Harel of the Weizmann Institute of Science. *(photo from wis-wander.weizmann.ac.il)*

Harel believes that such systems will eventually exist, pointing out that research is continually improving our understanding of how smell is “encoded” and how we perceive it. Although reasonably good sniffers and whiffers exist, the tantalizing scientific challenge is to work out the algorithm for connecting the sniffer’s reading into the whiffer’s emission; that is, a method is needed for translating any given odour into precise instructions for the whiffer to follow. The output mixtures would have to be experienced by humans in the way that photos are today – as reproductions that our sense recognizes as faithfully capturing the original.

Despite the fact that this challenge appears to be extremely difficult, Harel recently devised a test that could be used to assess the validity of such a system, if and when one is proposed. One of his inspirations was the Turing test proposed by the British father of computer science, Alan Turing, to test claims of human-like intelligence in a machine. A tester sits in one room and holds conversations with entities in two other rooms – one a human and the other the candidate computer. Through questions, chitchat and serious discourse, the tester tries to identify which is which; if repeated tests cannot distinguish the computer from the human, it is said to possess artificial intelligence. “The problem with using such a test for artificial olfaction,” said Harel, “is that such blind comparisons are detached from the element of human recognizability; and there is no adequate language to describe smells in general, meaning verbal discussions would not work either.”

Harel devised a “lineup” test, whose key feature is the immersion of odours with their natural audio-visual references, thus eliminating the need for verbal description. A team of neutral testers is given several short video clips – for example, of a bakery, a zoo, a dusty attic, a flowering meadow, etc. – and is asked to match an odour emitted by the sniffer with its correct clip. The clips are prepared by a team of challengers, whose role is to try to disprove the claim that the proposed system is valid.

To make sure that the test is fair – for example, the subjects won’t be required to identify the odour of a damp cave hidden from view in the clip of a meadow scene – the group is divided into two. One half is exposed to the actual odours collected and preserved at the video sites, and the other to the artificial, chemically reproduced odour created by the sniffer-whiffer system. That way, the second team of participants – those smelling the whiffer output – are required only to correctly match the odour to its clip when the first team – those exposed to the real odour – succeeds. As in the Turing test, the artificial is pitted against the natural in a blinded experiment, but here the test uses odour immersion for recognizability, and the test is asymmetric, requiring from the artificial no more than is required from the real thing in order to be declared successful.

For more on the research being conducted at the Weizmann Institute, visit wis-wander.weizmann.ac.il.