Materials on the Edge

English
 
 
(l-r) Yoav Lahini, Mor Verbin, Yaacov Kraus, Oded Zilberberg and Zohar Ringel
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
The story begins in two separate locations in the Institute’s physics buildings. In one of those – the lab of Prof. Yaron Silberberg – research students Yoav Lahini and Mor Verbin were experimenting with a quasicrystalline optical system. Quasicrystals, discovered 30 years ago by Prof. Dan Schechtman of the Technion, are unique in the arrangement of their atoms: Like regular crystals, they are arranged in an orderly fashion but, unlike most crystals, that arrangement is not periodic. Quasicrystals represent a new type of matter; recognition of this fact changed the face of materials science and forced scientists to redefine the meaning of the term “crystal.” Schechtman received the 2011 Nobel Prize in Chemistry for his discovery, which garnered interest among crystallographers, chemists, physicists and mathematicians alike. Yoav and Mor, who were studying a new type of optical quasicrystals developed in the lab, had noticed some strange, inexplicable phenomena taking place at their crystals’ edges. They measured, but could not explain, these phenomena.

In another part of the physics buildings, research students Oded Zilberberg in the group of Prof. Yuval Gefen, Yaacov Kraus in the group of Prof. Adi Stern and Zohar Ringel in the group of Prof. Ehud Altman were becoming interested in the new field of topological materials. These materials, discovered in 2007, are mostly normal, periodic crystals, but they have unusual electrical properties: The interior of the material acts as an insulator, but its surface conducts electricity just as if it were coated with metal. Like the discovery of quasicrystals, these new materials forced scientists to rethink accepted views – in this case, that a material was either an insulator (in which electrons don’t move) or a conductor (in which electrons can easily flow). Since then, scientists have been searching for additional topological materials, both with a view to possible applications and to investigate their unique properties.
 
 
A SEM figure of the etched waveguides composing the optical quasicrystal
 
These three students asked themselves whether quasicrystals might have topological properties. A certain overlap among various studies hinted that the answer might, at least partly be positive: Topological materials and quasicrystals can both be described, in some sense, as “projections” of higher dimensional systems. Yet the models of quasicrystals they worked with did not reveal topological phenomena.
 
The first meeting of these two ideas occurred far from the Weizmann campus. Yoav and Oded ran into each other by chance on a fine Saturday afternoon in Tel Aviv. While chatting, the two realized that their respective research efforts could be complementary, and a meeting was soon set up between the theoretical group and the experimental one.

Working together, the five students succeeded in showing – in theoretical work and in experimental measurement – that quasicrystals do, indeed, have topological properties. In some ways these newly-discovered properties are similar to those of “regular” topological materials, but in other ways they are very different.

In experiments conducted in Silberberg’s lab, the students built a quasicrystal using an array of coupled thin optical fibers etched with a powerful laser beam into a single glass cube. The parallel fibers were arranged at quasiperiodic (non-repeating) distances. When light was shined into a central fiber in this system, it “hopped” to the other fibers, emerging from all the fibers at the other side. But when the light was introduced at one of the far edges of the array, it remained confined to that side. In other words, the quasicrystal setup showed an “edge state” with different properties than the states found in the middle of the array. Just as electrons in topological materials flow only on the surface and do not penetrate the interior, the light shined through the outer edge of the optical quasicrystal setup stayed in that plane. This finding was a surprise, as scientists had believed such topological behavior to be impossible in a one-dimensional system.
 
An adiabatic light pump: (l) The setup: The spacing between the optic fibers is slowly varied to induce light pumping. (r) Measurements of the intensity distribution as the light moves down the quasicrystal show it crossing from right to left
 

 

 
In an additional experiment, the team varied the distances between the optic fibers, so that they were no longer parallel along their entire length. When they got the arrangement just right, light going into a fiber at one edge hopped across the entire array, exiting from the fiber at the opposite edge. Though somewhat unexpected, this phenomenon, called an “adiabatic pump,” supplied further proof that the quasicrystal system had topological properties.

Adiabatic pumps are known from a different kind of topological system called a quantum Hall system, in which electrons are exposed to directional magnetic fields. The model the students developed to explain this behavior enabled them to envision the optical quasicrystal setup as a sort of one-dimensional cross section of a two-dimensional quantum Hall system. That cross section, to the team’s surprise, preserves the topological properties of the two-dimensional system. In other words, one-dimensional quasicrystals “inherit” their topological properties from higher-dimensional “ancestors,” which are periodic crystals.

These findings were recently published in Physical Review Letters, and they were highlighted in Science and other scientific journals. Now, among other things, the team is checking whether their results are applicable to other dimensions. For instance, the theory they developed suggests that topological properties in three-dimensional quasicrystals can be linked to topological systems existing in six dimensions.
 
Dr. Ehud Altman's research is supported by the Yeda-Sela Center for Basic Research; and the estate of Ernst and Anni Deutsch.

 
Prof.Yuval Gefen is the incumbent of the Isabelle and Samuel Friedman Professorial Chair of Theoretical Physics.
 
Prof. Yaron Silberberg's research is supported by the Crown Photonics Center, which he heads; the Cymerman - Jakubskind Prize; and the European  Research Council. Prof. Silberberg is the incumbent of the Harry Weinrebe Professorial Chair of Laser Physics.


 
 
 
(l-r) Yoav Lahini, Mor Verbin, Yaacov Kraus, Oded Zilberberg and Zohar Ringel
Space & Physics
English
  • Adi Stern
  • Condensed Matter Physics
  • Ehud Altman
  • Optics
  • Physics of Complex Systems
  • Topological material
  • Yaron Silberberg
  • Yuval Gefen

Life Begins at 80

English
 
 

 

Prof. Victor Zalgaller at 90
 

 

In the spring of 2000, Prof. Victor Zalgaller had an extraordinary dream: It revealed to him the proof of a geometrical theorem. The revelation was not entirely out of the blue; Zalgaller had spent an entire year thinking about that theorem day and night. Armed with Zalgaller’s proof, a colleague of his managed to solve a 50-year-old mathematical problem. Their joint success, its results published later in the prestigious Annals of Mathematics, was one of the best presents Zalgaller received for his 80th birthday.
 
A more formal celebration, a mathematical meeting in honor of his 80th birthday, was held at the Weizmann Institute of Science in December 2000. When Zalgaller had immigrated to Israel from Russia a year earlier, he had been appointed a Consultant in the Institute’s Department of Mathematics.
 
Zalgaller’s ties with some of Weizmann’s mathematicians go back a long way: Back in 1946, Prof. Michael Solomyak had decided to become a mathematician after studying in a mathematics class for ninth-graders taught by Zalgaller at the Leningrad Pioneer Palace. Other faculty members and students at Weizmann know Zalgaller through his contributions to various areas of mathematics, including convex polyhedra, linear and dynamic programming, differential geometry and isoperimetry. He is perhaps best known for the 1980 book Geometric Inequalities that he co-authored with a former student, considered a classic and translated into English.
With his father Abram, 1955
 

 

Victor Abramovich Zalgaller’s lengthy journey to geometry reflects the many tribulations Soviet mathematics went through in the 20th century. As a youngster, he had joined one of the evening mathematics classes created in Russia in the mid-1930s to remedy the abysmal state of higher education, including mathematics, resulting from the Bolshevik policy of admitting students to university on the basis of ideology and class origins rather than ability. In 1936, he was among the winners of one of the first Leningrad Mathematics Olympiads for high school students.
 
His studies at Leningrad State University were interrupted by World War II. In early July 1941, after the Nazis invaded the USSR, he volunteered for the Red Army and spent the next four years in the artillery on the front line, sustaining a severe injury and earning five military decorations for bravery. In his memoirs Wartime Life, published in the United States in 1972, he documents his experiences in chilling detail, from the 1941 defense of the Leningrad District to the 1945 march through defeated Germany.
During the defense of Leningrad, 1942
 

 

Upon return to university, Zalgaller’s status as a war veteran helped to make up for the two major obstacles he faced in his career as a mathematician in the Soviet Union: being Jewish and being the son of a father who in 1931, on trumped-up charges of propaganda for Poland, had been sent to the Gulag and had never been allowed to return to Leningrad. These “shortcomings” notwithstanding, in 1948 Zalgaller joined the Leningrad branch of the Steklov Institute of Mathematics, affiliated with the USSR Academy of Sciences, where he was to work for more than 50 years. From the 1970s, he also served as a professor at Leningrad University, where he was one of the most popular lecturers.
 
Early in his career, he worked under the guidance of famous mathematician Leonid Kantorovich, who was later to win the Nobel Prize in Economic Sciences. In 1951, they co-authored Economic Cutting of Industrial Stocks, one of the first books in the world on this topic. “I’m proud that upon receiving the Nobel Prize, Kantorovich named me among those who had helped him,” Zalgaller recalls.
Zalgaller (right) with his mother and brother Lev, killed on the front in WWII
 
He also considers himself fortunate to have worked closely with yet another famous Soviet mathematician, Alexander Danilovich Alexandrov. In 1962, they co-authored a book in Zalgaller’s main area of research, geometry: Intrinsic Geometry of Surfaces.
 
In addition to co-writing the three books, Zalgaller has translated another three and served as scientific editor of twelve more; his small book, Theory of Envelopes, is still widely used by engineers. He has authored more than 100 research papers; five of these papers were published after he turned 80.
 

Since making Aliya, Zalgaller lives in Rehovot. His wife Sofia-Maia is also a mathematician; in 1980, they co-authored a paper, later translated into French, in which they proposed the first algorithm for solving the Rubik’s cube puzzle from any initial position. They have a daughter, Tatiana, a computer specialist in the hi-tech industry, as well as a grandson and four great-grandchildren.  

                                                                

Prof. Victor Zalgaller (front row, second from right) and other participants of the meeting marking his 90th birthday at the Weizmann Institute
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Zalgaller’s 90th birthday was marked at the Weizmann Institute by a mathematical meeting that focused on his contributions to research. But on the same occasion, his colleagues also praised his qualities as a human being, particularly his exceptional honesty and his generosity in sharing his knowledge with others. Says Solomyak, now a Professor Emeritus in the Mathematics Department: “Mathematicians are judged not only by their own research, but by the benefit they bring to the scientific community, by the kinds of problems one can discuss with them. Zalgaller is exceptional in that you can fruitfully discuss with him a huge portion of mathematics.”
 
 
 
Prof. Victor Zalgaller
Math & Computer Science
English
  • Algorithm
  • Geometry
  • Mathematical proof
  • Mathematics
  • Michael Solomyak

A Poet of Science

English
 
Aharon Katzir
 
The link between science and morality is a leading theme in Prof. Aharon Katzir’s book In the Crucible of Scientific Revolution, published just months before he was murdered in a terrorist attack at Ben-Gurion Airport 40 years ago. Katzir believed that scientists hold a multi-faceted responsibility toward society: “Science has ceased being of interest to professionals alone; it has become an enormous societal force whose impact on society’s structure, on people’s interactions and on international politics cannot be ignored.” Throughout his life, Katzir remained faithful to his own credo: In conducting versatile studies, he searched for scientific truth while staying committed to the State of Israel and to humanity at large.

Katzir was born in Poland in 1913 into the Katchalsky family. (He Hebraized his name in the 1950s when he was sent to the Soviet Union on a scientific mission at David Ben-Gurion’s request, thus becoming one of the first Israeli scientists to cross the Iron Curtain). Immigrating to Eretz-Israel with his parents at age 12, he lived in Jerusalem and later studied biology and chemistry at the Hebrew University, enrolling in 1932 with the university’s first generation of students in the natural sciences. In addition to science, he was committed to public activity, and he co-founded a socialist youth movement while a student. During the War of Independence, he worked toward strengthening the young country’s security in parallel with conducting scientific research as a newly minted Ph.D. at the Hebrew University. He co-founded the science corps of the Israel Defense Forces, Hemed, which helped win the war and subsequently served as the basis for Israel’s security industries.

In 1948, Dr. Chaim Weizmann invited Aharon Katzir and his brother Ephraim to join the Weizmann Institute, then in advanced stages of planning. Ernst David Bergmann, the emerging institute’s scientific director, said years later that he had been fascinated by Aharon when he came to Rehovot to discuss the possibility of serving as a department head at the Weizmann Institute: “Some people thought he was too young to assume such a responsibility, but who could resist the charm of a young scientist, brimming with plans and ideas while searching for an enterprise he could build from scratch?”
 

 

Katzir in his lab, 1972
 

 

Katzir founded the Institute’s Department of Polymers and headed it until his assassination. In his scientific research, he strove to understand the basic processes of life. He chose to study the function of large synthetic molecules, particularly those whose behavior could shed light on major phenomena in living systems. This research led him to the new field of mechanochemistry, which addressed the conversion of chemical energy into mechanical energy, much like the processes taking place in our muscles. Katzir received worldwide recognition for his work in this field.

In one of his last scientific undertakings, Katzir used the theory of thermodynamics of irreversible processes in order to develop a mathematical theory that described the permeability of biological membranes – one of the central issues in physiology and life in general. This mathematical theory was soon accepted by researchers throughout the world. Some of its principles, today considered classic, are still being applied worldwide in science and industry – for instance, in designing membranes for desalination. This work won Katzir and his former student Prof. Ora Kedem the Israel Prize in 1961.

Katzir contributed a great deal to placing Israel on the map of world science. He was among the first Israelis to hold senior posts in international scientific organizations, including President of the International Union for Pure and Applied Biophysics. He was a member of three scientific academies in the United States and received honorary degrees from numerous universities in different parts of the world.
(l-r) Profs. Ephraim and Aharon Katzir, date unknown
 
In Israel, alongside his basic research, Katzir helped to found numerous institutions that today form an inseparable part of Israel’s intellectual life. He founded the Israel Academy of Sciences and Humanities and served as its president for six years, until his death. Among others, he was instrumental in the creation of Ben-Gurion University of the Negev, the Van Leer Jerusalem Institute and the Feinberg Graduate School at the Weizmann Institute.

Katzir pioneered the popularization of science in Israel. His World of Science popular lectures on the radio drew enthusiastic listeners. A charismatic teacher, he trained hundreds of students. According to Kedem, his Ph.D. students felt as if they were being inducted into the temple of science. When he visited the Soviet Union in the late 1950s, it was the only time that a lecture by a foreign visitor at the University of Moscow had to be transferred to a larger hall.

In May 1972, Katzir was on his way home after attending several conferences in Europe, including a German-Israeli meeting on membranes he had organized in Göttingen with Prof. Manfred Eigen, Nobel laureate in chemistry. At Ben-Gurion Airport, he and other passengers were attacked by Japanese terrorists. About 100 people were wounded in the shooting; 24 of them died, including Katzir.

Few people know that in his youth, Katzir had seriously considered becoming a poet and was a member of the Eretz-Israel Mandolin Orchestra. His wide-ranging interests encompassed, among numerous others, Judaism, literature, philosophy of science, theories of morality, education and information theory. Prof. Shneior Lifson, his former student, called him “a poet of science.”

Prof. Katzir’s life and work is commemorated in Israel and abroad. At the Weizmann Institute, the Aharon Katzir-Katchalsky Center furthers international scientific cooperation through conferences and the exchange of scientists. “Of particular concern to the Center is the impact of scientific and technological advances on human society,” says its mission statement. All three of Katzir’s children chose to follow in his scientific footsteps: Abraham Katzir, a physicist; Yael Katzir, an anthropologist; and Gadi Katzir, a marine biologist.

Special thanks to Orna Zeltzer, Weizmann Institute Archive.
 
 
 
 
Katzir in his lab, 1972
English
  • Aharon Katzir
  • Biophysics
  • Chaim Weizmann
  • Ephraim Katzir
  • Feinberg Graduate School
  • Polymer

The Deep Blue

English

 

Seagoing research team (l-r) Uri Sheyn, Dr. Miguel Frada, Shlomit Sharoni, Daniella Schatz, Dr. Assaf Vardi and Dr. Yoav Lehan

 

 

 
 
 
 
 
 
 
 
 
 
 
At night, on a swaying deck thousands of kilometers from land, with the salt spray in one’s eyes, one truly understands the concept that all life on Earth – from the tiniest marine bacterium to humans – is afloat on the same small boat. Just ask some of the 30 scientists who recently participated in a one-month Atlantic research cruise to investigate the life cycles of the trillions of tiny, single-celled, plant-like creatures that float in the ocean’s waters. These creatures, called phytoplankton, are the basis of the marine food chain: Without them, there would be no life in the oceans and not enough oxygen to support life on our planet.

After setting out from Ponta Delgada in the Azores, the ship headed north and continued up the middle of the Atlantic to Reykjavik, Iceland. One of the five research teams aboard the ship, from the Weizmann Institute’s Plant Sciences Department, was led by Dr. Assaf Vardi. Says Vardi, the voyage was more than just a research trip to investigate the role of phytoplankton in the environment – it was also a social experiment: “Take a few dozen people from different countries, pack them into a small space and stir; place them in the middle of the ocean and then add a bit of tension and a good dollop of scientific curiosity. And what do you get?”
 
 
Dr. Assaf Vardi and Dr. Miguel Frada. Catch of the day

Of algae and people


Phytoplankton can sometimes, for unknown reasons, multiply very rapidly. This causes algal blooms that can extend for hundreds, and even thousands, of kilometers – large enough to be seen from space. And then, all at once, the bloom collapses and disappears. Understanding how these blooms grow and collapse is critical: The oceans’ phytoplankton absorb as much carbon dioxide as the world’s rain forests, so they could be important allies in the effort to reduce global warming; and the sustenance they supply to the marine food chain is vital for keeping the world’s population fed.

Vardi and his colleagues had previously discovered that viruses are responsible for algal bloom collapse. Like viruses everywhere, these invaders insert their genes into their host’s cells. In the case of those that attack the phytoplankton, these virus genes produce enzymes that, in turn, produce fat molecules called sphingolipids. Interestingly enough, these sphingolipids are very similar to certain human ones that have been implicated in a number of diseases, but they had never been found to be produced by viruses. Vardi: “These enzymes and mechanisms have been conserved throughout evolution, and they function in an extremely wide variety of organisms.”

Vardi had discovered a cellular mechanism in the phytoplankton that senses the accumulation of sphingolipids and initiates a programmed cell death sequence called apoptosis. Apoptosis is well-known in multicellular organisms: Damaged or used-up cells take their own lives for the good of the whole. But what use is cell suicide to a single-celled organism? How do the cells withing the phytoplankton community communicate so that some survive, even as others lose their lives? How does this affect the ecology of the oceans as a whole? These are a few of the questions that the researchers on board have been attempting to clarify.

According to recent findings of Vardi and others, phytoplankton are actually not so keen on the idea of suicide, and they at first resist the invading tide of viruses with an entire arsenal. In a dramatic evolutionary arms race, they fight with chemical weapons, military maneuvers, head-on attacks and evasive end runs – all conducted on the molecular level within the phytoplankton cells. Multiplied by billions of cells, such molecular processes can determine the very course of the earth’s bio-geochemical pathways and, ultimately, the climate. And the fact that these pathways have been preserved throughout evolution means that researchers can study them in phytoplankton and apply them to humans. For instance, certain substances these marine organisms use to fight viral invasion might be effective against those that cause disease in humans, while research into the mechanisms of cell death in these simple creatures could lead to new ways of initiating cell death – in cancer cells, for instance.
 

 

Dr. Assaf Vardi
 

On the briny, in search of a bloom


On the ship’s deck, the research teams brought up water samples from different depths. These were tested in on-board research labs. Vardi: “For two weeks, we sailed without seeing a single bloom. And then we found one. That was an unforgettable moment of relief, on the one hand, and a shot of new energy, on the other, to go back out and keep working 20-hour days to continue our research efforts.”

In addition to these studies, Vardi’s team was involved in a unique collaboration with a group in the Institute’s Environmental Sciences and Energy Research Department to investigate the feedback cycle that includes marine biology (especially algal blooms) and tiny particles called aerosols in the atmosphere that affect cloud formation. Though highly complex, this feedback cycle could play a significant role in climate change, and understanding it might clear up a few open questions in the field.
 
 
“This effort,” says Vardi, “was the first of its kind to focus on all levels simultaneously, from molecular processes within the cell to cellular processes and up to the behavior of whole populations spread over thousands of kilometers. Working right alongside the ocean’s surface, accompanied by whales – this was a one-time experience. Every day, there was a brand-new sunset, until we neared the Arctic Circle and experienced the midnight sun there. Those are things that none of us will ever forget.”
sunset on a research ship
 
Meanwhile, back in his Weizmann lab, researchers have already begun experiments on the thousands of samples now stored there. In these samples, they are searching for clues to the mechanisms of life, to cycles in the environment, to the ways that tiny, single-celled creatures can drive the earth’s natural cycles.
 
Dr. Assaf Vardi’s research is supported by Charles Rothschild, Brazil; Roberto and Renata Ruhman, Brazil; Luis Stuhlberger, Brazil; and the European Research Council. Dr. Vardi is the incumbent of the Edith and Nathan Goldenberg Career Development Chair.
 
 
 
Seagoing research team (l-r) Uri Sheyn, Dr. Miguel Frada, Shlomit Sharoni, Daniella Schatz, Dr. Assaf Vardi and Dr. Yoav Lehan
Life Sciences
English
  • Alga
  • Apoptosis
  • Assaf Vardi
  • Environmental Sciences and Energy Research
  • Lipid
  • Ocean
  • Plant Sciences
  • Virus

Workplace: On the Ice

English
 
 
Dr. Hagar Landsman at the geographical South Pole
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dr. Hagar Landsman (Peles) smiles when she talks about Antarctica – the featureless landscape, the - 40°C temperatures in summer, the relentless midnight sun. “It’s a very special place,” she says. Landsman has already made two trips to the South Pole, and she hopes to go again in the next southern summer – sometime between November and February.

Landsman is a member of the international “IceCube” research team – IceCube being a unique sort of telescope, one that tracks particles called neutrinos, rather than light. Though quite common, neutrinos are almost impossible to detect. They are nearly without mass and carry no charge, and they very rarely interact with normal matter. The only way to detect them is to look for signs of those rare interactions.

In recent years, science has revealed much about these elusive little particles – for instance, the fact that they can change from one type to another as they zip through space – but many mysteries remain. One of those mysteries is the source of certain high-energy neutrinos connected with cosmic phenomena known as gamma ray bursts. Observing neutrinos from these bursts might help researchers understand their origins and how they are produced. Neutrinos are also believed to be connected to mysterious cosmic rays and could shed light on puzzling phenomena that have been observed in these rays. In addition, neutrinos might yield clues to the unseen side of the universe – dark matter. “People have been using photons (light) to observe the universe since the dawn of history,” says Landsman. “In IceCube we use neutrinos for astronomy, which gives us a fresh and exciting view.”
 
 
at the pole
Landsman has been working on IceCube for the past eight years – since receiving her Ph.D. in physics from the Technion, Haifa, and going on to postdoctoral research at the University of Wisconsin. Her main responsibility has been calibrating and testing, and ensuring that all of the 5,000 detectors now buried under the Antarctic ice function properly.

Completed just last year, IceCube is an enormous array of light detectors, one cubic kilometer in size, buried at a depth of 2.5 km below the polar ice. At this depth, there is total darkness. Yet rare bursts of light occur in those infrequent cases in which a neutrino interacts with the million tons of ice. Down there, the ice is crystal clear, and a burst of light can travel hundreds of meters, reaching a number of IceCube’s light detectors.
 

 

arrival
 
Each basketball-sized detector, says Landsman, undergoes several months of rigorous testing and calibration. Once it is encased in ice, there is no moving or repairing it. Yet it is expected to function for the next decade. At the South Pole, Landsman retests and readjusts the detectors one last time before sending them down the boreholes into place.

Trips last a month – three weeks “on the ice” and another week in transit – though the Antarctic’s unpredictable weather can extend travel time by days. In those three weeks, Landsman works nearly around the clock, not just because it is light 24 hours a day, but because she feels the need to accomplish as much as possible in the short time she has there. “All of the 150 or so people at the South Pole Station – researchers, engineers and support staff – work this way. The cost of bringing a person there is so high that only truly necessary people are allowed. Housekeeping chores – from cleaning toilets to washing dishes – are shared by all.”
 
 
into the Borehole
 
Most of Landsman’s work is outdoors. At an elevation of 2,800 m, altitude sickness is a problem, and the extremely dry air is even more troublesome than the cold. The conditions slow the work down: “If you forget a screwdriver, it can take two hours to go back and get it,” she says. Indoors, the station is kept cool to save on heating, and showers are limited to two minutes twice a week. “One gets used to it all,” says Landsman. And once in a while, the work stops for entertainment – for instance, the Christmastime “race around the world”:  a circumpolar run accompanied by snow vehicles fitted out as parade floats by the station’s engineers.


A change of scenery


Landsman’s most recent work trip was much closer to home – to Italy. At the Weizmann Institute, Landsman is a member of the Particle Physics and Astrophysics Department in the group of Profs. Ehud Duchovni, Eilam Gross and Amos Breskin. Specifically, she is a key member of the Weizmann team participating in the XENON project, which is attempting to find evidence for dark matter particles with a detector deep underground in Italy’s San Grasso National Lab. The team is now building a new detector that will hold a ton of liquid Xenon. Landsman is involved both in data analysis and in planning the new device.
 
 
 
She is also involved in planning and installing the next neutrino project at the South Pole. Known by the acronym ARA, the new project will eventually be 100 km. sq, with detectors spaced a kilometer apart. The new detectors work with radio waves, rather than light waves, and can thus be placed under just 200 m of ice. Landsman describes ARA as “a really big net, designed to catch the biggest fish” – in this case the highest-energy neutrinos.

Hagar is married to Adi, who is also on the IceCube team. Because he is involved with the administrative side of the project, work takes him to Wisconsin, rather than Antarctica. But he is pleased that the $300 million dollar project was completed on time, and slightly under budget. The couple has a daughter and a son, who, according to Hagar, don’t quite understand what their mother does on her trips. “When she was younger, my daughter told everyone her mother was going to Antarctica to feed neutrinos to the penguins.”
 
IceCube research station
 

 

 

Waiting for a particle


Earth’s atmosphere is under a constant barrage of extremely high energy cosmic rays – exceeding a hundred million gigavolts. (That’s a million times the energy of the most energetic particle created in a lab.) The source of these particles and their means of production are still unknown. The Weizmann Institute’s Prof. Eli Waxman and the late Prof. John Bahcall proposed that these particles are produced near young black holes with masses similar to that of the sun, and that such black holes are also responsible for the production of strong gamma ray bursts. One of the central aims of the giant IceCube project in Antarctica is to test this theory, by searching for high-energy neutrinos that are predicted to be produced alongside the cosmic rays and gamma rays. As yet, the detector has not found these high-energy neutrinos, but according to the model proposed by Waxman and Bahcall, the number of neutrinos this detector is likely to record is relatively tiny, so that data will need to be collected over a period of five to ten years before any conclusions can be drawn.
 
 
landsman
 
Prof. Amos Breskin’s research is supported by Erica A. Drake and Robert Drake; the Nella and Leon Benoziyo Center for High Energy Physics; the estate of David Turner; and the Friends of Weizmann Institute in memory of Richard Kronstein. Prof. Breskin is the incumbent of the Walter P. Reuther Chair of Research in Peaceful Uses of Atomic Energy.
 
Prof. Ehud Duchovni’s research is supported by the Friends of Weizmann Institute in memory of Richard Kronstein; the Nella and Leon Benoziyo Center for High Energy Physics; and the Yeda-Sela Center for Basic Research. Prof. Duchovni is the incumbent of the Professor Wolfgang Gentner Professorial Chair of Nuclear Physics.

Prof. Eilam Gross’s research is supported by the Friends of Weizmann Institute in memory of Richard Kronstein.
 
Prof. Eli Waxman heads the Benoziyo Center for Astrophysics. Prof. Waxman is the incumbent of the Max Planck Professorial Chair of Quantum Physics

 
 

 
 


 

Dr. Hagar Landsman at the geographical South Pole
Space & Physics
English
  • Amos Breskin
  • Ehud Duchovni
  • Eilam Gross
  • Eli Waxman
  • Hagar Landsman
  • Neutrino
  • Particle Physics and Astrophysics
  • Particle detector

Israel Prize to Prof. David Milstein

English

Prof. David Milstein recieves the Israel Prize. In the recieving line (from third from left): Education Minister Gideon Sa'ar, President Shimon Peres, Prime Minister Benjamin Netanyahu, Knesset Speaker Reuven Rivlin and Chief Justice Asher Grunis

 

 

 
On Israel Independence Day, the Institute’s Prof. David Milstein received the 2012 Israel Prize for chemistry and physics. The Israel Prize is the country’s highest honor.
Interactions between metal atoms and organic molecules are at the heart of Milstein’s work, and he is a leader in the field of organo-metallic chemistry. Based on principles he discovered, including new ways to selectively activate chemical bonds, he developed novel catalysts that are environmentally friendly: They work with low energy input and mild conditions, emit no pollutants and do not require the addition of harsh chemicals.

In 2007, Science magazine cited as one of ten “breakthroughs of the year” his group’s development of a ruthenium-based catalyst to convert starting compounds, called amines and alcohols, directly into another class of widely useful compounds, called amides, which play crucial roles in chemistry and biology. This catalyst, called the “Milstein catalyst,” is used today in labs around the world. Two of Milstein’s catalysts are now being marketed worldwide by Strem Chemicals, Inc. and a major multinational corporation has shown strong interest in a third.

In other recent work, Milstein has not only demonstrated greener ways of producing vital organic compounds but has also developed new chemical reactions for sustainable energy. For instance, in 2009, he devised a two-step sequence that uses sunlight to split water into hydrogen and oxygen, and releases no chemical waste. Crucial to the process is a completely new way of generating an oxygen (O2) molecule.

Yet another new reaction process developed in Milstein’s lab may, in the future, lead to practical methods for turning waste carbon dioxide (CO2) into fuel. New versions of the organic-metal catalysts were used to create methanol from CO2. The chemical reaction is both green and mild, and fuel production based on this method could recycle greenhouse gasses in the process. In the latest research to come out of his lab, yet another new ruthenium-based catalyst was used to produce primary amines – compounds that are widely used in the chemical and pharmaceutical industries. These compounds are generally produced at high pressures and temperatures, and generate a fair amount of waste; but the new method works at low temperatures and pressures, and yields are selective for the desired compound with no waste.

Milstein studied under Prof. Jochanan Blum at the Hebrew University of Jerusalem, receiving his Ph.D. in 1976. His postdoctoral research was conducted at the University of Iowa and Colorado State University, where he invented, together with his adviser John K. Stille, the Stille reaction, which is widely used for the generation of carbon-carbon bonds. He then went on to work in the Central Research and Development Department at DuPont Co. (Wilmington, USA). Milstein joined the Weizmann Institute faculty in 1987. In 1996, he was appointed Head of the Organic Chemistry Department, a position he held for three consecutive terms. In 2000, he founded the Kimmel Center for Molecular Design, and he continues to head this Center today.

Prof. David Milstein’s research is supported by the Helen and Martin Kimmel Center for Molecular Design, which he heads; the Bernice and Peter Cohn Catalysis Research Fund; and the European Research Council. Prof. Milstein is the incumbent of the Israel Matz Professorial Chair of Organic Chemistry.
 

 
 
 
Prof. David Milstein recieves the Israel Prize. In the recieving line (from third from left): Education Minister Gideon Sa'ar, President Shimon Peres, Prime Minister Benjamin Netanyahu, Knesset Speaker Reuven Rivlin and Chief Justice Asher Grunis
Chemistry
English
  • Catalyst
  • David Milstein
  • Israel Prize
  • Organic Chemistry

Heart and Mind

English

Profs. Bernardo Vidne and Talila Volk. From human hearts to fruit fly hearts

 

 

 
“Never say ‘I’ve achieved all my goals’,” says Prof. Bernardo Vidne. “Once you’ve crossed everything off the list, that’s when you start to die.”

Vidne has always taken his own advice. Until a few years ago, he was head of cardiac surgery in one of the largest hospitals in Israel. Today, at just over 70, he is a Ph.D. student at the Weizmann Institute. As an esteemed surgeon, he was addressed respectfully as “professor,” had a comfortable office with a secretary and walked the halls of his hospital dressed in pressed pants and a tie, followed by a coterie of students and doctors. Today, he wears jeans and T-shirts and sits at a corner desk in the lab, wedged between two other students. “I never imagined I would have such a great retirement,” he says.

Bernardo Vidne grew up in a poor family in a small Argentinean town, Basavilbaso, near the Uruguayan border. The town had a large Jewish population, having originally been settled by Russian Jewish immigrants in the late 1800s, and Vidne was drawn to its Zionist youth movement. After high school, he spent a year in Israel in a program for international Zionist youth leadership. When he returned to Argentina, he took an active role in recruiting students to Zionist youth groups while working in a winery to support himself. But he soon found he wanted a career and enrolled in medical school.
 

More than a job


In 1964, at age 24, Vidne arrived by ship at Haifa port with his new bride, Naomi. He was about to realize two of his dreams: Working as a doctor and living in Israel. Though he was first offered a position as a general practitioner in a clinic in the small desert town of Dimona, he decided to begin his medical career as a general surgeon, soon moving to hospital work in Soroka Medical Center in Beersheba.
 
But Vidne had already set other goals for himself. Ever since medical school, he had wanted to be a heart surgeon. He went to study with Prof. Maurice Levy, one of the top cardiac surgeons in the country at the time. That is how Vidne assisted in the first heart transplant in Israel in 1968, just a year after the very first one had been conducted in South Africa.
 
All four babies underwent heart surgery in the same week
 
In a career spanning 35 years, Vidne performed over 40,000 heart surgeries. At age 38, he established a cardiac surgery department in Ichilov Hospital, Tel Aviv, later heading the department in Beilinson Medical Center in Petah Tikva when his mentor, Maurice Levy, retired. He specialized in pediatric heart surgery, performing some 10,000 operations on children, including tiny preemies born with heart defects – the youngest, born prematurely at 770 gr., underwent open heart surgery in his first week of life. In addition, Vidne taught many students and published some 300 papers in medical journals.

“Medicine was not just a job,” says Vidne. “It was my life. I went to sleep thinking about my patients; at parties and performances, my heart was still back in the hospital. So much so, that I encouraged my children to go into any field but medicine. I was unsuccessful in this with my daughter, but two of my sons became engineers, and a third recently finished a Ph.D. in mathematics at Columbia University.”
 
Among the honors he has received (including an honorary doctorate from Cordoba University, where he studied medicine in Argentina), was an international Golden Hippocrates Award in 2003, the highest honor awarded for cardiac surgery.
 
 

The next goal


Even in the midst of his busy career, Vidne was looking for the next goal. At one point, he says, he thought about trying biological research and even wrote the Weizmann Institute to inquire about the possibility. When he was told that he would have to leave his job to study full-time, he decided that research might end up on his list of unfulfilled dreams.

And then, one day, as his retirement date neared, he received an email describing a new MD/Ph.D. program at the Weizmann Institute, designed to allow medical doctors to continue their practice part-time while conducting Ph.D. research in the life sciences. Vidne picked up the phone and called. “When I told them my age, they didn’t fall off their chairs, but they did tell me it would be hard work. I said: ‘I’ve sought hard work all my life. I just can’t make a firm promise that I’ll be around to finish the degree.’”

Vidne felt he already had a connection to the Institute, because its sixth president, Prof. Michael Sela, had been a patient. But he began his studies like every other student – with preparatory courses and an examination (12 units in all). “My titles and medical experience, my published papers – none of these prepared me for advanced molecular biology,” he says. “It was like finding myself in China without understanding a word of Chinese (and I know what that’s like – I’ve been there).”

Fortunately, the perseverance that had served him throughout his medical career helped him here, as well. He is now conducting full-time research in the lab of Prof. Talila Volk, in the Molecular Genetics Department, with the goal of earning a Ph.D.
 
Prof. Vidne in the OR
 

From humans to fruit flies


For the past two years, instead of operating on human hearts, Vidne has been investigating the hearts of fruit flies. He and Volk believe that genes in a fruit fly’s heart cells might contain clues that could facilitate understanding how to help repair human hearts. Until a few years ago, it was thought that the heart was one of the few final, “eternal” organs – organs in which the cells are never replaced over a person’s lifetime. Now we understand that a small group of cells can regenerate, but they are not enough to prevent the cardiac disease that appears in nearly 30% of the population. By contrast, some organisms can grow new tissue when as much as 20% of their heart is removed. Vidne and Volk are now attempting to identify and understand the molecular mechanisms behind this feat. They suspect that many of the genes for fruit fly heart renewal may exist in humans, as well, but are kept dormant. “That,” says Vidne, “will provide research material for future generations.”

“The world of research here is amazing,” he says. “I don’t know how the other students see me – some are not much older than my grandchildren. But they are fantastic, and I learn from them every day. I’m already looking forward to finishing my Ph.D. and going on to my next goal in life – which is to continue researching.”
 
Prof. Talila Volk’s research is supported by the Y. Leon Benoziyo Institute for Molecular Medicine. Prof. Volk is the incumbent of the Professor Sir Ernst B. Chain Professorial Chair.

 
 


 

 
Profs. Bernardo Vidne and Talila Volk. From human hearts to fruit fly hearts
Life Sciences
English
  • Fruit fly
  • Heart disease
  • Michael Sela
  • Molecular Genetics
  • Talila Volk
Yes

At the Helm

English

Inauguration of the Weizmann Institute of Science, November 2, 1949

 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
It was with great sorrow that Dr. Benjamin Marcus Bloch gave up on physics to take on the management of the Daniel Sieff Research Institute at the request of Dr. Chaim Weizmann, who, in addition to his political engagements, served as the Institute’s President. For Dr. Bloch, it was a fateful decision. For the Institute, it was the start of a tradition of high standards in management.
 
In the early 1930s, Dr. Bloch was a young physicist in Brussels. Behind him was a lengthy journey across Europe. He was born in April 1900 in the Austro-Hungarian Empire, in the Galician town of Delatyn where he spent his childhood, the youngest of nine children in a traditional Jewish family. He studied physics at Prague’s German University and worked, during his student days and afterwards, as a journalist in the German-language newspaper Prager Tagblatt. Upon completing his studies with honors, he stayed on at the university as a research assistant. Several years later he moved to Belgium, as a senior researcher in the chemical physics department of the Brussels’ Université Libre, in the area of infrared spectroscopy.
 
Walking with Weizmann, 1947
 
During that time, Dr. Chaim Weizmann was planning to establish a physics department in the Sieff Institute he had founded in Eretz-Israel. In the summer of 1934, he invited Benjamin Bloch to come over and take this mission upon himself. Bloch welcomed the offer as an opportunity to combine Zionism with science. He initially joined Dr. Weizmann’s team in London, then in the fall of 1935 arrived in Rehovot with his wife Bronia, an ophthalmologist, and their baby daughter Rivka. In Eretz-Israel, the couple would give birth to two more daughters, the twins Navah and Naomi.

As there was a delay in the establishment of the physics department, Dr. Bloch started helping Weizmann in managing the Institute (a challenging task, in view of budgetary difficulties and research requirements). He revealed such talents in this area that, in 1936, Dr. Weizmann asked Bloch to continue working with him in the management of the Institute. Bloch accepted the offer; he was to fill this position with great success for nearly 25 years.
 
Even though Bloch, then 36, was much younger than Weizmann, the two became close friends. Dr. Vera Weizmann, Chaim Weizmann’s wife, wrote years later: “My husband had full trust in Dr. Bloch, in his fairness and integrity. Dr. Bloch, for his part, was a loyal friend of my husband’s, fulfilling his work with faith and precision.”

Dr. Bloch missed physics a great deal and mourned its loss. He occasionally told his family and friends, referring to the loss of his siblings in the Holocaust: “I used to have a brother and seven sisters – but no more; I used to have my physics – but no more.”  Nevertheless, says his daughter Navah: “I recall Felix Bloch (no relation), the Nobel laureate in physics who was a friend of my father’s, saying that in terms of personal fulfillment, he would have gladly changed places with my father.”
 
During World War II, when Dr. Weizmann spent much time in London, Bloch assumed even greater managerial responsibilities. With the inauguration of the Weizmann Institute in 1949, he was appointed its administrative director. The Institute’s scientists and staff admired and respected him not only as a manager but as a human being. In 1952, at a meeting of the Board of Directors of the American Committee for the Weizmann Institute in New York, Meyer Weisgal, then Chairman of the Institute’s Executive Council, proposed to express special thanks “to Dr. Bloch, who has been the conscience of the Institute since 1934. He has had to grapple with enormous problems in his daily administration; he has had heartaches and difficulties in dealing with a staff of 300 people, and scientists could sometimes be as temperamental as artists. Yet the Institute is one of the very few public institutions in Israel which in the 18 or 19 years of its existence has never had a strike.” On other occasions, Institute scientists Aharon Katzir and Amos de-Shalit, as well as many others, lavished praise on Bloch, expressing their appreciation for his commitment to the Institute, as well as for his contribution to the Institute’s strength. Bloch and his wife hosted in their home numerous high-ranking guests of the Institute, among them the physicists Robert Oppenheimer and Niels Bohr.

 
With Prime Minister of Burma U Nu, 1955
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
In addition to his managerial responsibilities at the Institute, Dr. Bloch contributed a great deal to numerous emerging organizations of the young State of Israel. He was a board member of Magen David Adom (Israel's emergency medical service) and of the Israel Maritime League; as a representative of the Institute, he served on national scientific councils before and after the establishment of Israel. During World War II, he was active in the national defense committee and in the Haganah. His daughter Navah recalls that he used to tell her and her sisters: “We are building a country, we are building industry.” In the summer of 1955, Bloch represented Israel at a session on the peaceful uses of atomic energy, organized by the USSR Academy of Sciences in Moscow. At the session he spoke in Russian – one of the many languages he knew.
 
In his late fifties, Dr. Bloch had plans to return to physics but, sadly, he fell ill. He went for treatment to the United States but passed away in a New York hospital in April of 1959, just one day before the celebration of the 25th anniversary of the Institute, to which he had devoted such a significant part of his life. He was buried in Rehovot. Thousands took part in the funeral: When the funeral procession left the Weizmann Institute, Rehovot residents lined both sides of the road; as the procession passed the police station, the policemen saluted Dr. Bloch on his final journey.
With Robert Oppenheimer, 1958
 
At the Weizmann Institute, Dr. Bloch has been commemorated in a variety of ways: Student scholarships have been created in his name and a room in the physics building was named after him (it is scheduled to be re-dedicated in the near future). But most prominent, of course, is the lovely tree-lined road that leads from the Institute’s historic entrance to the heart of the campus: Benjamin Bloch Avenue.

Special thanks to Navah Bloch Rodrig and to the Weizmann Institute Archives for help in the preparation of this article.
 

 

 

 

 

 


 

 
Inauguration of the Weizmann Institute of Science, November 2, 1949
English
  • Aharon Katzir
  • Amos de-Shalit
  • Benjamin Bloch
  • Chaim Weizmann
  • Daniel Sieff Research Institute
  • Physics

Potential for Renewal

English

Standing: (l-r) Yoach Rais, Leehee Weinberger, Drs. Abed Mansour, Noa Novershtern and Jacob (Yaqub) Hanna, Sergey Viukov, Itay Maza and Mirie Zerbib. Sitting: (l-r) Dr. Ariel Pribluda, Vladislav Krupalnik, Gilad Beck, Ohad Gafni and Shay Geula

 

 

 

 

 

 

 

 

 

 

 

 

The potential of embryonic stem cells is almost unimaginably huge. From one undifferentiated cell, an entire organism composed of diverse and widely varied tissues and organs is created. Now, scientists are looking to expand the potential of these cells: As medical tools, they might be used to restore injured cells and tissues, and help to treat such genetic conditions as autoimmune diseases and degenerative nervous system disorders. “The main hurdle that stands in the way of medical embryonic stem cell application today is getting the stem cells to differentiate properly. We still don’t know how to reproduce that process efficiently, precisely and in quantity,” says Dr. Jacob (Yaqub) Hanna, who recently joined the Institute’s Molecular Genetics Department. In his new Institute lab, he and his research team will try to answer basic questions on the mechanics of stem cell differentiation and development, in hopes of advancing the use of stem cells in medicine. 


Embryonic stem cells are completely undifferentiated – that is, they have the potential to become any cell type. During embryonic development, they go through a series of developmental stages, and these are strictly regulated such that each decision on the way is perfectly timed and executed; mistakes in the process can spell disaster. For scientists, these cells are a research treasure, enabling them to reproduce entire developmental processes in a lab dish. Hanna grows them in various conditions, using genetic engineering and other methods to address the basic questions: How do embryonic stem cells preserve their potential to develop? How is regulation – complex, yet finely tuned – carried out during differentiation? How is the fateful decision – to differentiate or not to differentiate – reached? And what can experiments carried out in a lab dish tell us about the development of an embryo, especially a human embryo?
 

Colony of mouse embryonic stem cells, stained blue and green
 

Sending cells back in time


Another area of stem cell research that interests Hanna is a recent breakthrough: Several years ago, scientists demonstrated that mature, adult skin cells could be “sent back in time,” to return to their embryonic stem cell state. Surprisingly, this reprogramming was accomplished with the insertion of only four genes into the adult cell genome. Creating stem cells from adult cells solves various ethical problems inherent in using embryonic stem cells from human eggs or embryos. But there could be other advantages, as well. Patients with certain diseases could be treated with their own cells, avoiding the need for matching donors. Cells taken from a person with a genetic disease could be reprogrammed into stem cells; genetic engineering techniques would then be used to repair the genetic cause of the disease, and the renovated stem cells directed to undergo the required differentiation before being reimplanted in the patient.  
 
 
In his postdoctoral research, Hanna and his lab partners were the first to prove the feasibility of this method, showing it could cure sickle cell anemia in mice. In another investigation – into why reprogramming is successful in only a small percentage of adult cells – he found a number of “main switches” all of which must be turned on for the process to complete itself. To gain a better understanding of the mechanisms involved in transforming a cell from one type to another, Hanna plans to uncover the exact functions of these switches and find out why they are so important. Another approach, says Hanna, will be to investigate how an egg can easily do what scientists struggle to achieve: In the lab, it can reprogram adult cells to generate perfect embryonic stem cells.

In addition to the goal of unraveling the basic mechanisms of differentiation and development, and his longer-term aims in the field of regenerative medicine, Hanna says that stem cell research can supply new, sorely needed tools for research into human gene-based diseases, among them Type 1 diabetes, Parkinson’s and Alzheimer’s. These diseases involve degeneration of the cells, making them hard to study. But Hanna plans to create stem cells from the adult cells of patients. He can then apply such genetic engineering methods as inserting or removing genes, or adding markers to create useful models for researching these diseases – hopefully opening up new pathways to developing treatments.  
 
Green-stained embryonic stem cell colony surrounded by differntiated neurons (red)
 

Award winning researcher

 

Dr. Jacob Hanna was born and raised in Rama, in the Galilee, into a family of doctors: His grandfather, father and three sisters are doctors. In keeping with the family tradition, he studied medicine at the Hebrew University of Jerusalem, but found he was attracted to research, preferring hours in the lab to treating patients. “My uncle, a scientist who heads a pharmaceutical firm, was my influence and inspiration. This uncle was behind the development of the first antibody approved for the treatment of lymphoma.” In 2007, Hanna completed a combined MD/PhD program, magna cum laude. His postdoctoral research was carried out with Prof. Rudolf Jaenisch of the Whitehead Institute for Biomedical Research at the Massachusetts Institute of Technology (MIT). His research there won him a number of awards; among them, in 2010 he was named one of the 35 innovators under 35 by Technology Review. In 2011, he joined the Molecular Genetics faculty of the Weizmann Institute.
 


Hanna lives in Tel Aviv. Most of his free time is spent on his favorite hobby – scientific research. But in addition, he manages a Tel Aviv bar together with three good friends.         
 
Dr. Jacob Hanna's research is supported by the Sir Charles Clore Research Prize; the Leona M. and Harry B. Helmsley Charitable Trust; Pascal and Ilana Mantoux, France/Israel; and the European Research Council.
 

 

 
 
 
Colony of mouse embryonic stem cells, stained blue and green
Life Sciences
English
  • Genetic disease
  • Jacob Hanna
  • Molecular Genetics
  • Stem cell

Divine Secrets of the Ant Sisterhood

English
 
 
ant communcations
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
“In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed,” wrote Darwin. Ants, a family that has inhabited the earth for about 100 million years, must be one of the most magnificent manifestations of such biological cooperation. Thousands of female ants pull together in a coordinated effort to ensure that all the needs are met for the proper functioning of the entire colony. (The males’ only role is to mate with the queen, and once this is completed, they die). While some ants forage, others stay behind to tend the brood, or to build, maintain or defend the colony’s living quarters; and there are even those whose task it is to bury the dead. But the thing that makes their behavior so remarkable is that they have no leader – no boss or governing body to allocate and manage their activities.  How exactly do ants collaborate and divide the labor among themselves so successfully and altruistically?

In his new lab in the Physics of Complex Systems Department, Dr. Ofer Feinerman and his team are hoping to reveal some of the ants’ secrets in a collaborative effort of their own, using tools from such fields as information theory, statistical and theoretical physics, computer science, systems biology, neuroscience and, of course biology. “Biology is rife with complex systems consisting of individual components – proteins, cells, organisms – organizing themselves into networks to coordinate their activity. While biology is able to identify and describe the individual components, the interactions between them can get very messy and analyzing such data can become overwhelming. By borrowing tools from physics and math, more quantitative measurements can be used to discern the rules that govern such complex collective behaviors,” says Feinerman.
Dr. Ofer Feinerman. Complex communications
 

Social networking


Ants primarily “speak” to one another in the language of chemicals: If an ant finds a rich food source, for example, it will deposit a trail of pheromones that tells the other ants where to find it. Social networks are formed between the ants during such communication, and it is these networks that Feinerman wants to understand.

In a setup reminiscent of Big Brother, Feinerman has handpicked a number of native Israeli ants to enter an artificial, nest-like structure that has cameras dotted around, enabling his team to eavesdrop on the ants’ “conversations.” Each ant is identified by a barcode glued to its back, enabling the scientists to track and record its activities. The scientists are hoping to answer such questions as: Who “speaks” to whom? Do ants form cliques and only interact with those in the same group, or are they indiscriminate? Do they employ far-reaching social networking tools akin to, say, Twitter or Facebook, relying on others to “retweet” and “share” their messages? Do messages get passed down a line of ants, or would an ant prefer to wander far and wide to make sure the message is relayed accurately?

Feinerman: “Ants use different communication strategies, ranging from one extreme to the other, depending on the setting. For example, in ‘piggybacking,’ one ant rides on top of another; though slow, this is a very reliable and direct method of communication, appropriate, for example, for ensuring the second ant arrives at the exact food location without getting lost along the way. Other situations may warrant less focused, but faster, forms of communication. For example, if a colony comes under attack, the ants spray pheromones into the air. This alarm system rapidly warns other, distant colonies of potentially imminent danger.”

Slow and reliable or fast with some compromise: Understanding ant communication and social networking strategies will do more than help reveal the intricate workings of an ant colony; they also assist in the long term goal of using this rich cooperative system to develop a theory of collective information processing. Ultimately, the researchers would like to develop the tools needed to answer fundamental questions about other complex biological systems: for instance, how immune system cells work together to fight infection. Such tools could also have practical applications in the design of so-called distributed systems, including cellular communication antennae, wireless sensor networks or even groups of robots engaged in rescue operations.
 

Empire of the Ants


At the head of each ant colony is a queen; but, though “royalty,” she does not possess any sovereign power over the worker ants – her sole duty is to lay eggs. With no ruler, how do ants divide labor? Do some ants belong to “elite” units, with others relegated to more “lower-class” duties? Or are they all equal?

In previous research, Dr. Feinerman investigated whether certain factors – previous experience, age, body weight, spatial location – determine how tasks are allocated. One way to test this is to see how ants respond to increased demands in certain tasks. For example, when food stores are running low, which ants take it upon themselves to aid in the foraging effort? Or offer a helping hand to nurse an extra brood in the colony?

The ants were placed in an artificial, two-chambered nest, and the scientists manipulated the task load by withholding food or adding new members to a brood. Again, the ants were individually tagged – this time using radio-frequency identification (RFID) – to identify individuals that responded.

This study revealed that it is the leaner ants that are usually on the frontline: They are the first to respond to increased foraging needs, even when other factors (age, experience and spatial location) are taken into account. They also seem to be the ones who engage in transporting the newly planted brood members to the main brood pile. However, lean ants do not seem to actually help in tending the brood. In fact, Feinerman found that brood care seems to be random, not dependent on by age, experience or weight, but rather, by whoever happens to be passing by.
 
 
Barcoded ant in the lab of Dr. Ofer Feinerman
 

“With regard to foraging, sending out the leaner ants could boost colony survival, as they would be more expendable in the risky task of foraging, may attract fewer predators, and might even be more mobile than their heavier counterparts. Likewise, the fact that brood care seems to be open to all suggests that flexibility in general task allocation, and collaboration on the whole, is more valuable  than, say, expertise or experience, as it allows for a rapid response to a changing environment, thereby ensuring the survival of the colony,” says Feinerman.


ANT-thropologist


Dr. Ofer Feinerman was born in Rehovot, Israel, and he earned a B.Sc. in physics and mathematics summa cum laude (1996) and an M.Sc. in physics (1999), both from the Hebrew University of Jerusalem. As a Ph.D. student at the Weizmann Institute of Science, under the guidance of Prof. Elisha Moses, he grew the first artificial logic circuits made of nerve cells, earning his doctorate in 2006. He then conducted postdoctoral research for three years at the Memorial Sloan-Kettering Cancer Center in New York, investigating how the immune system's T-regulation cells work together to fight infection. Feinerman spent one year studying ants at Rockefeller University before joining the Department of Physics of Complex Systems at the Weizmann Institute of Science as a Senior Scientist in October 2010. “Coming back to the Weizmann Institute was a dream – not only did it give me the opportunity to return to Israel, but it also gave me the freedom to study ants – a somewhat unconventional subject. For this I am eternally grateful to and proud of the Weizmann Institute.”

Feinerman is married to Micka, a mosaic artist, and has three children: Matan (9), Shai (7) and Nomi (4).
 
Dr. Ofer Feinerman's research is supported by the Clore Foundation.
 
 


 

 
Barcoded ant in the lab of Dr. Ofer Feinerman
Space & Physics
English
  • Communication
  • Elisha Moses
  • Ofer Feinerman
  • Physics of Complex Systems
  • Social behavior›Social behavior
  • Systems biology

Pages