The Fingerprint of a Diamond

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William Levine (center), a prominent American diamond merchant, inspecting gemprints during his visit to the Weizmann Institute in 1974, with Prof. Shmuel Shtrikman (left) and Dr. Charles Bar-Isaac (right)
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dr. Charles Bar-Isaac was in love when he traveled from Israel to Iran in the early 1970s: His goal was to meet the family of his future wife, Lillian. But in Teheran, Bar-Isaac, then a student at the Weizmann Institute of Science, encountered his second love. When visiting the exhibition of Iran’s crown jewels in the national bank, he was dazzled by the display of spectacular diamonds, among them the more than 3,000 diamonds studding the Pahlavi Crown and the world’s largest uncut diamond called The Sea of Light. Upon returning to Rehovot, he decided to focus his doctoral research on diamonds.
 
Lillian’s pendant. A turquoise inset is surrounded by 20 small diamonds
 
The Iraqi-born Bar-Isaac, who had immigrated to Israel with his parents at age six in 1950, earned a master’s degree in physics from the Hebrew University of Jerusalem before embarking on Ph.D. studies in what was then the Weizmann Institute’s Electronics Department, under the supervision of Profs. Shmuel Shtrikman and David Treves. In his doctoral thesis, he applied laser technologies and the principles of the area of physics known as Fourier optics to the study of diamonds. What attracted him to these gems was not just their beauty; he was fascinated by the physics of the aesthetic experience: How beauty is revealed by the light interacting with the precious stone.
 
It is the light reflected, refracted, dispersed and absorbed by a stone that determines such crucial properties as the gem’s brilliance and color. Diamonds stand out in their brilliance among all other gems because when exposed to light, they sparkle from virtually every angle. Throughout history, diamond cutters and jewelers sought out, by trial and error, the best ways to cut and polish the stones, until in 1919 in London, a young mathematician and physicist, Marcel Tolkowsky, developed a mathematical formula for cutting diamonds in an optimal manner. The process, which calls for cutting 58 facets on a diamond to provide maximum reflected light and brilliance, came to be known as the “ideal cut.” Today, most diamonds in the world are cut according to this principle. When Bar-Isaac started looking into the science behind the “ideal cut,” he was amazed to discover that even though the diamond industry had existed since biblical times – in the Book of Exodus, Moses is instructed to make a breastplate set with diamonds among other gems – several of its central issues had remained unresolved. One major issue, for instance, was how to definitively establish the identity of a particular diamond – a task that becomes especially crucial in police work when stolen diamonds are recovered, or in the frequent disputes between jewelers and customers who claim the stone returned after setting and cleaning is not the same one they left.  
 
Using as a model the exquisite diamond-framed pendant that Lillian had received from her mother, Bar-Isaac realized that the light scattered by each diamond carries a deal of information about the stone. That was how he came up with the idea for Gemprint: an optical system for “fingerprinting” diamonds by recording the angles and intensities of the reflected light rays, which form distinctive patterns. Since no two stones – no matter how similar they may look – create the same pattern, a comparison of their “fingerprints” can serve for positive identification.
Calculated gemprints, created by computerized ray tracing, reveal the difference between different cuts
 

 

In the system, a low-density laser beam shines upon a gem; its reflection pattern is then digitized and stored. Apart from positive identification, the method provides a means of quantifying beauty: It assigns measurable values to a diamond’s brilliance and can therefore be used in its grading – that is, establishing its quality. It can also help determine whether the diamond had been produced according to the ideal cut.
 

After registering a patent for Gemprint in the mid-1970s, Yeda Research and Development Co. Ltd., the Weizmann Institute’s technology transfer arm, licensed the system for commercial manufacture in Israel and elsewhere. Within a few years, Gemprint came into wide use in the diamond industry.

Two gemprints of the same stone, taken at different times, reveal themselves as identical when they are superimposed
 
Bar-Isaac decided not to continue scientific research after completing his doctorate in 1975, opting instead for a career in photography. He then left Israel, ultimately settling in London with Lillian and their three children.
 
As for Gemprint, the Weizmann Institute patent has in the meantime expired, but the system continues to be used around the world by diamond dealers, jewelers, insurers and professional appraisal services. Accepted as evidence of a gem’s identity in courts of law, it has helped to obtain convictions and return numerous lost or stolen diamonds to their rightful owners. International databases that hold the information about hundreds of thousands of diamonds are continuously being expanded with the gemprints of new precious stones.   
 

 
 
 
 
William Levine (center), a prominent American diamond merchant, inspecting gemprints during his visit to the Weizmann Institute in 1974, with Prof. Shmuel Shtrikman (left) and Dr. Charles Bar-Isaac (right)
Space & Physics
English

Taking Flight

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bat in flight

 
 
 
 
When Dr. Michael Yartsev first got in touch with his soon-to-be mentor Dr. Nachum Ulanovsky, it was because he wanted to inquire about Ulanovsky’s own former PhD adviser, as he was thinking of applying for a PhD position in that adviser’s lab. But when Ulanovsky, a neurobiologist who was then finishing up his postdoc in the US, started talking about his own research and his plans for setting up a lab at the Weizmann Institute, says Yartsev: “I thought ‘this research program is risky, extremely innovative and exciting – which is exactly what I am looking for.’ That is how I became Nachum’s first student.”
Dr. Michael Yartsev
 
Yartsev, who grew up in Beersheba, completed his BSc and MSc in biomedical engineering at Ben-Gurion University of the Negev. There, he worked on recording the activity of single neurons in the cerebellum of awake, behaviorally active cats. By the time he completed his degrees, he says, he had fallen in love with neuroscience and was looking around for an exciting place to do his PhD. He decided to join Ulanovsky’s group even before the latter returned to Israel. “It just felt so right,” he says.

Ulanovsky works with bats, both in his lab in the Neurobiology Department and in the wild. His lab contains a darkened, soundproofed “bat cave” equipped with visible-range and infrared cameras and microphones that enable him and his team to investigate the bats’ highly developed spatial navigational abilities. The Egyptian fruit bats they work with, says Yartsev, “are extremely intelligent animals and, once they get used to you, they are also pretty friendly...at least most of them.” The key to working with these animals, he found, is to respect the fact that each individual bat has its own unique personality; acknowledging this is the key to getting their cooperation.
 
 
Yartsev’s research focused on two specialized classes of cells in the mammalian brain: the place-cells in the hippocampus and grid-cells in the entorhinal cortex. These cells are widely believed to be pivotal for spatial memory and navigation – whether in humans, rodents or any other mammals. While much of this research is done with rats, bats gave Ulanovsky’s group a unique advantage: They enabled the researchers to examine problems similar to those that rodent researchers have been grappling with for a long time, but from a completely different perspective – one that has turned out to be very useful. For example, questions such as the neural mechanisms of 3-D navigation have proved impossible to address using standard animal models.

In their first set of experiments with the bats (published in Nature in 2011), Yartsev and Ulanovsky investigated how the grid cells create a map-like network in the brain. In the process they disproved the most widely accepted class of computational models of grid cells – models that were based solely on rodent experiments. In a second set of experiments (published in Science in 2013), they used tiny, wireless devices to measure the activity of individual neurons in the bats’ brains as they flew around an artificial tree in the lab. Using this innovative technology, the researchers were able, for the first time, to observe how the place cells in the bats’ brains perceive three-dimensional, volumetric space and to answer the question: Do they relate equally to all three axes of space? (The answer is yes, each cell appears to be almost equally sensitive to all the three spatial axes in the room.)  
 
Dr. Nachum Ulanovsky
 
In addition to the scientific papers, Yartsev wrote an essay describing their work with bats for studying the neural basis of the mammalian spatial representation system. That essay, which appeared in Science, made him the 2013 grand prize winner for the prestigious Eppendorf and Science Prize for Neurobiology. He also recently received the Donald B. Lindsley Prize in Behavioral Neuroscience from the Society of Neuroscience. Yartsev is the first Israeli student to receive these prestigious prizes.

Admitting to enjoying the recognition his work has received, Yartsev emphasizes that for him the real prize has been the experience and knowledge he gained in the process: “It has truly been an honor and a privilege being Nachum’s first student, and I envy all of those who will be his students in the years to come. Being part of this lab has truly been a wonderful experience.”

At present, Yartsev is a CV Starr Fellow at Princeton University, where he is conducting postdoctoral research in the lab of Prof. Carlos Brody. There he is investigating the neural basis of decision making, including how the brain rapidly routes information to guide choices and how new information is integrated into the process. Along the way he is acquiring new techniques for studying the brain, among them optogenetics – a method for controlling neural circuits with light.

In the future, he intends to return to researching bats. “I plan to use these incredible animals to study how information available in the environment around us guides our actions, choices and decisions,” he says.

Yartsev is married to Liza and they have a five-year-old son, Ariel. They enjoy traveling together, and especially relish new places and new experiences.


 
 
 
(l-r) Drs. Michael Yartsev and Nachum Ulanovsky
Life Sciences
English

Second Generation

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(l-r) Drs. Harry and BenjaminTowbin and Nora

“I just want to make it clear that I had nothing to do with my son’s decision to come here; that was completely his own choice,” says Dr. Harry Towbin. Towbin, recently retired from the Federal Institute of Technology (ETH), Zurich, completed his PhD at the Weizmann Institute close to 40 years ago. He and his wife, Marion, were recently at the Institute visiting their son, Dr. Benjamin Towbin, who is currently a postdoctoral fellow in the Institute’s Molecular Cell Biology Department.

After completing his MSc at ETH, Harry had decided to continue his studies in Israel – he felt the need for a “change of atmosphere.” He had previously been to the country as a tourist and to visit family in Tel Aviv. “This was in the days before Internet,” he says. “So I got on a plane and spent a few days staying with my relatives and looking around.”

In 1973, Harry ended up in the lab of Prof. David Elson in Weizmann’s Biological Chemistry Department, where he worked on the structure of the ribosome. A short time after he arrived, the Yom Kippur War broke out. Research in the lab ground to a halt as its members were called up, so Towbin and a friend went to volunteer on a kibbutz in the south of the country, helping out in the chicken coops. Soon enough, however, the lab work started up again.

Towbin found the relatively small, intimate size of the Institute and its research groups to his liking. When Marion, whom he had met in Switzerland, finished her studies in pharmacology, the two married and she joined him in Israel. Harry continued his research, and Marion found a position as a lab technician in the neurobiology lab of Prof. Zvi Vogel.

“We got to know the country quite well,” says Towbin, “especially the desert. We both like to hike, and we miss the desert when we are in Switzerland.”

When the Towbins returned to Switzerland, Harry took up a position at the Friedrich Miescher Institute (FMI) for Biomedical Research in Basel. There, he and his colleagues developed the technique for the Western blot tests used today in almost every biology lab in the world. “Some elements of the technique were inspired by the work done in David Elson’s lab,” he says. Harry then moved to the pharmaceutical company, Ciba-Geigy, which would later become Novartis. In his lab there, he continued conducting basic research in immunological chemistry. When the company downsized, just as he was turning 60, Towbin retired and accepted an invitation from ETH to join its faculty. Now he is there part time, mainly consulting and working with students, which he greatly enjoys. “As a scientist, you never completely break with your work,” he says.

Benjamin, the younger of Towbin’s sons, was also drawn to scientific research. (His older brother is an economist.) He completed his PhD in Basel, at FMI, but he already knew he wanted to conduct postdoctoral work outside the country. Both he and his wife, Christine, were familiar with Israel, making it a comfortable choice. But what truly attracted Benjamin was the research of Prof. Uri Alon of the Weizmann Institute’s Molecular Cell Biology Department. Benjamin had been following Alon’s work in the field of systems biology for a number of years. “I found it exciting,” he says. So when Alon spoke at a conference in Basel, Benjamin approached him and Alon ended up inviting him to the Weizmann Institute.

At the Institute, Alon arranged for Benjamin to meet with a number of research groups. “All of them were fascinating,” he says, “but I ended up in Uri’s group, as had been my initial plan.” Benjamin is an experimental “wet-lab” biologist; his PhD research in molecular biology focused on the spatial organization of the DNA in the nematode C. elegans. Now he is investigating regulatory gene networks in the bacterium E. coli. “This is my chance to learn something new,” he says. “The group is made up of experimentalists and theorists, and what I am learning from the theorists is helping me rethink my experiments.”

Benjamin, Christine and their 1 1/2-year-old daughter live in Rehovot, near the Institute. Christine is starting a postdoc in environmental sciences: She transferred from her research group in Switzerland to that of Dr. Itay Halevy in the Institute’s Earth and Planetary Sciences Department. After being here for six months they are happy with their choice, says Benjamin, not least because they have found Israel to be a very child-friendly place. They have been made to feel very welcome, he adds, having received valuable help both from members of the lab and from the Institute’s Visiting Scientists Department.

For Harry and Marion Towbin, having a child and grandchild in Israel gives them an excuse to visit more often. Such visits include meetings with Institute researchers who have been his colleagues for some 40 years, among them Profs. Moshe Oren and Zvi Vogel. And they still take the opportunity to hike in the desert – the day after being interviewed, the family was on their way south from Rehovot on a hiking trip through the Ramon craters.
 
 

 

(l-r) Drs. Harry and BenjaminTowbin and Nora
Life Sciences
English

A Life in Science

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Ora (Katz) Kedem made aliyah to Israel with her parents in November 1940, arriving on the last ship allowed to leave German-controlled Austria. But the ship was intercepted by the British blockade against Jewish immigration to the country, and passengers were transferred to another ship, the Patria, bound for detention on the island of Mauritius. To protest the deportation policies of the British mandate, members of the Hagana had planted a bomb on board – but the explosion caused more damage than anticipated and the Patria sank rapidly. The Katz family, along with around 2,000 other passengers, had to swim to the lifeboats. Ora was meant to be on kitchen duty that day in the ship’s hull – a place from which few managed to escape – but by chance she had agreed to switch places with another passenger. Though she was just 16, she took charge of saving her family, managing to get her ailing mother and another passenger who did not know how to swim to safety. Around 200 immigrants and a number of British soldiers drowned in the bombing.

 

The Patria sinks in view of Haifa port, 1940
 
 
 
Upon reaching shore with nothing but the wet clothes on their backs, the passengers were met by local citizens (the “Yishuv”) who provided them with dry clothes. The British police transferred them to the detainment camp at Atlit, where they received modest but adequate shelter, food and beds; in the new arrivals’ view, these were wonderful after all they had been through. Ora did not stay there long: After teaching herself Hebrew (in addition to the lessons given in the camp), she enrolled in the Levinsky Seminar for teachers, hoping to realize her dream of becoming a teacher in Israel. While studying, she helped support her family by working as a cleaner and tutoring in physics, as well as helping care for her frail sister.

Ora stood out among the young women at the Seminar for her unusual interest and accomplishments in physics; her physics instructor, Alexander Barelli, encouraged her to join a support group for physics teachers, and it was then that she decided that her true place was at university. Ora studied hard for the entrance exams to the Hebrew University of Jerusalem. Her efforts granted her not only a place at the University but a cash prize of 28 Israeli liras – enough money at the time to help fund her studies and cover some of her living expenses. In her first year of studies, Ora also joined the Hagana and underwent a training course for squadron leaders.
Prof. Ora Kedem in her Weizmann Institute lab
 
By the outbreak of the War of Independence, she had managed to complete a master’s thesis on the absorption of bromine at the Hebrew University’s Mount Scopus campus under Prof. Ladislaus Farkas, founder of the Chemical Physics Department there, and Dr. Rudolph Bloch, the head scientist at the Dead Sea Works. To conduct her research, she had constructed her own specialized glass instruments.

During the War, Ora served in the Science Corps of the Hagana under the command of Prof. Aharon Katzir. During the siege of Jerusalem they made flares and land mines, among other things. Ora was responsible for a group of young women who prepared the materials. She met Abraham Kedem, the man whom she would later marry, while on guard duty: He was responsible for the mechanics of the Corps.
 
 
When Ora arrived at the Weizmann Institute, she was still a member of the Hagana Science Corps, but she soon began work on her doctoral research under Katzir. As before, she built her own lab equipment, with some help from the Institute’s technical staff. Here she also received such “exact” instructions as: “Parts for instruments are to be found in the warehouse; assemble as described in the literature.”

Because the young institute lacked experts on many subjects, each of the students adopted a subject, researched it and lectured on it to the others in group seminars. Ora took upon herself the subject of membranes. By chance she came upon a book on plant physiology describing experiments that tied in closely with the theoretical work on membranes with which she was familiar, and this serendipitous connection led her to author, with her mentor, Prof. Katzir, a number of articles on transport in biological membranes. These articles, published beginning in 1957, opened new horizons in their field, and they were enthusiastically received. This research earned Prof. Aharon Katzir and Ora Kedem the Israel Prize for the natural sciences in 1961. She has been researching membranes ever since, and her achievements in the field have led to international recognition.
 
(l-r) Weizmann Institute Profs. Ora Kedem, Nathan Sharon and Ephraim Katzir
 
In 1967, the head of Israel’s Atomic Energy Commission, Prof. Israel Dostrovsky, invited Kedem to join its research facility in the Negev. There she was given the task of reorganizing the chemistry department. She established a tradition of recruiting young talent and, at the same time, she taught courses in the academic centers in Beersheva that would later become the Ben-Gurion University of the Negev.

In 1972, just as Kedem was returning from a sabbatical in Basel, Prof. Aharon Katzir was killed in a terrorist attack on the airport. She was asked to continue the membrane research at the Weizmann Institute, where she went on to found the Membrane Research Department – today the Biological Chemistry Department.

Kedem also had a hand in an early Israeli startup company. Together with Dr. Rene Bloch, a postdoctoral fellow in her group, she founded a company that was only the second firm to put down roots in the new Kiryat Weizmann Science Park, alongside the Institute. Their company, originally known as Research Products Rehovot, was later renamed Membrane Products Weizmann. In 1976, she served as scientific director of the company. She then retired from the Weizmann Institute, going on to join the faculty of Ben-Gurion University, first as an adviser and then, from 1995-2003, as head of the Desalinization and Water Treatment Department.

Prof. Ora Kedem has earned much recognition and esteem, as well as numerous prizes and honors, in part for her untiring efforts to find solutions to water quality problems in Israel. She has never stopped working: Recently, she and her husband, Abraham, added yet another patent to their name.    

 
 

 

 

 
Prof. Ada Yonath was nominated Honors Program Lecturer at New York University School of Medicine; received the 2008 Linus Pauling Gold Medal from Stanford University; and was named George E. Palade Distinguished Lecturer and Gold Medal recipient at Wayne State University.
English

We Learned How to Learn

English

“The time I spent at the Institute was the best period of my life,” says Dr. Danny Kandel, Senior Director of Advanced Development for KLA-Tencor, Israel. The Israeli branch of this international corporation, based in Silicon Valley, produces accurate metrology systems for quality control in the silicon chip industry.  Around 500 engineers and professionals work for the company in Israel, in two different locations.

Dr. Danny Kandel
Kandel was born in Kiryat Ono, near Tel Aviv. His parents had declined to enroll him in the activities for science-oriented children at the Weizmann Institute but, he says, that changed when he got a bit older and more “in control of my own fate.” In high school, he took programming courses offered by Tel Aviv University.  His army service, in a Nahal unit, included founding a new kibbutz in the Negev. Afterward, Kandel completed a B.Sc. in physics and mathematics at the Hebrew University of Jerusalem before coming to the Weizmann Institute.

His M.Sc. research, conducted in the group of Prof. Michael Kirson of the Particle Physics Department (today the Particle Physics and Astrophysics Department), focused on theoretical nuclear physics. Kandel remembers that period as intense but rewarding: “We worked very hard; the courses were especially demanding. But after all the hard work, we felt that we had actually succeeded in understanding things. There is no greater pleasure than understanding something really new about the world. All the effort, the long nights, the stress – these all vanished when we were washed by the waves of satisfaction that come with new comprehension.”

His doctorate (in statistical physics) was completed under the guidance of Prof. Eytan Domany of the Physics of Complex Systems Department. Kandel met and married Ditza Auerbach, then a doctoral student in the research group of Prof. Itamar Procaccia at the Institute. The couple had three children together while Kandel completed postdoctoral research at the University of Maryland and Harvard University, and then returned to the Institute as a senior scientist in the Physics of Complex Systems Department.

But Kandel was lured by the possibility of conducting research with more practical, industry-oriented applications, and he joined the research and development team at KLA-Tencor’s facility in Migdal Ha’emek. “They tell us that the ongoing shrinkage of electronic components will slow down, or maybe even stop,” he says, “but in the meantime, the components being produced industrially get smaller and denser every year. That presents a serious challenge for quality controllers, who must currently achieve a level of precision down to less than a single nanometer.”

Despite his duties as director of Advanced Development for the company’s Israeli branch, Kandel still keeps up his ties with Institute scientists, as well as with his former fellow students. “My studies at the Institute were an enlightening experience for me and my friends,” he says. “We learned how to learn. How to conduct research. How to ask questions; how to try to answer them. If you can do this, the sky is the limit. If you can do it correctly, you can do anything, invent anything.”  
 
KLA-Tencor logo
 
 
Quality control for silicon chips is a complex challenge: Measurement systems based on optics are limited to the length of a wave of visible light, around 400 nanometers. This is a crude tool for today’s electronics – the thickness of a line on a modern silicon chip is around 20 nm. That is akin to an elephant trying to feel a single grain of sand under its foot.  To get around this obstacle, the KLA-Tencor system makes direct and indirect use of a number of advanced optical and imaging techniques, including those based on light scattering from the object measured. The methods for processing these measurements to produce results were also developed by the company.
 


 

 
Dr. Danny Kandel
Space & Physics
English

Long-Term Vision

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Prof. Yael Hanein
 
Prof. Yael Hanein has a dream: to restore sight to the blind. Of course, this is a long-term vision, but her more immediate goal is also ambitious: to communicate with neural networks in the brain via nanotechnological devices.

Such communication poses a tremendous challenge because, among other things, it requires creating a bridge between two different worlds: that of physics and engineering on the one hand, and that of biology on the other, explains Hanein, Director of Tel Aviv University’s Center for Nanoscience and Nanotechnology. Communication in these two worlds is conducted in different languages: In “hard” engineering systems, electricity is transmitted by the flow of electrons, whereas in such “soft” biological systems as nerves, electrical signals are relayed by a flow of charged ions in a solution.

This means that a device implanted into the human body to replace damaged nerve tissue must not only be materially compatible with body tissues but also able to communicate with these tissues. How can the difficulties in “translation” be overcome?

Hanein proposes tackling the problem with implants made of microscopic carbon nanotubes. Thanks to their unique atomic structure, these nanomaterials combine elasticity with extraordinary strength. But perhaps most important is that the thin-walled tubes create an unusually large surface relative to their mass, which facilitates the transmission of signals from electrodes in these devices to nerves. In addition, nerve tissue clings firmly to their surfaces and grows well upon them. Devices fashioned in this way can greatly contribute to brain research, helping to clarify the biological basis of neurological diseases and the impact of drugs on the brain.

Hanein envisions one day implanting such devices into human eyes to replace retinas damaged, for example, by age-related macular degeneration, a common cause of vision loss in the elderly. The implant would transmit signals from the outside world to the brain in the neurons’ language.

A number of retinal implants have already been developed, including one that has been approved for use in humans in the United States and Europe. In Israel, such implants are being developed by Nano Retina, in which Hanein serves as a vice president. But according to Hanein, the entire field is still in its infancy: “It is still at about the same stage as the aeronautics industry when the first planes lifted off the ground and managed to fly for about a hundred meters.”

In her lab at Tel Aviv University’s School of Electrical Engineering, Hanein makes use of the scientific methods she learned during her master’s and doctoral studies in experimental physics at the Weizmann Institute’s Joseph H. and Belle R. Braun Center for Submicron Research: studying the flow of electrical charges, characterizing semiconductors, coating materials with nanolayers. Hanein’s doctoral research, under the guidance of Prof. Dan Shahar of Weizmann’s Condensed Matter Physics Department, focused on two-dimensional quantum Hall systems. She recalls: “From the moment I arrived at Weizmann as a student, I received all the resources – the scholarship, the access to labs. The message was: Just study and succeed.” Hanein now seeks to convey the same message to her own students: “My stint as a Weizmann student is still my example. The Institute gives students a home – the optimal environment for developing as a researcher.”

During her postdoctoral studies at the University of Washington in Seattle, she became interested in interdisciplinary research combining physics with chemistry, electrical engineering, materials science and biology, which led her to her current topic. Since returning to Israel and joining the faculty of Tel Aviv University in 2003, Hanein has received recognition for her work, in Israel and abroad. She was among the founders of the Global Young Academy and has lately been appointed a member of the Israeli Young Academy of the Israel Academy of Sciences and Humanities.

Hanein engages in her research with such intensity that during her leisure, she needs equally intensive activity to take her mind off work. Her favorite vacations have involved long hikes – in Ireland, Scotland and Japan – walking some 20 kilometers a day. In her other hobby, reading, she particularly enjoys history books that deal with human behavior at the level of groups or societies.

As a woman working in a traditionally male field, Hanein naturally gives much thought to the place of women in science. She is the only woman among 27 faculty members in the Department of Physical Electronics at Tel Aviv University; of the 66 scientists in the Center she directs, only eight are women. Hanein believes that in order to correct this situation, it’s important to determine how it comes about: “Electrical engineering can be a good profession for women, but its image needs to be changed. Just like the ‘gentler’ biomedical fields, it has applications that can help treat diseases and improve people’s lives.”

 
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Prof. Yael Hanein
English

Making Sense of a Complex Situation

English
Dr. Jasmin Fisher
              

 

 
“The world of biology is incredibly complex,” says Dr. Jasmin Fisher, who holds appointments at Microsoft Research, in Cambridge, UK, and Cambridge University. “The hand-drawn diagrams of biological processes I first learned to produce are static illustrations; they often don’t provide much insight into the highly dynamic interactions that occur. That is why I opened myself to the world of computation.” Today, Fisher is considered a world leader in a rapidly growing field of biological research in which computational models are the impetus for new discoveries.

Fisher came to the Weizmann Institute for her doctoral studies after completing a B.Sc. and M.Sc. in biology at Ben-Gurion University of the Negev. It was at Ben-Gurion, she says, that her adviser, Prof. Shai Silberberg, imparted the basics of science that she still applies every day: “Be a perfectionist in your work and learn to ask the right questions.”

At the Weizmann Institute, Fisher conducted her Ph.D. research in the neurobiology group of Prof. Michal Schwartz, investigating the dialog between the immune system and the central nervous system. Among other things, research in the group was changing ideas about the protective role that certain immune cells play in the brain and nervous system. In Schwartz, Fisher found an insistence on thoroughness that fit in with her own inclination, as well as a role model of an accomplished woman scientist.

Along the way, Fisher was coming to understand that the processing power of computers was needed to help life science researchers deal with the complexity of even the simplest living systems. So she stayed on at the Institute to conduct postdoctoral research with Prof. David Harel of the Computer Science and Applied Mathematics Department. In the 1980s, Harel had developed a visual programming language called Statecharts to deal with specifying and developing such complex systems as avionics. But he and others soon realized that biological systems could be described in much the same way as air-flight systems, and began applying tools like Statecharts to cells and organisms. “Because Statecharts is a visual language, it is easy for a non-programmer to use. Because it is state-based, it is an intuitive tool for describing biological mechanisms,” says Fisher. She joined the effort under way in Harel’s group to use computers to map out developmental processes in the nematode C. elegans, a model lab organism.

Her research took her next to Switzerland, to further her training in computational methods in the group of Prof. Thomas Henzinger at the Ecole Polytechnique Federale de Lausanne. There, she invented the term “executable biology” to describe the kinds of models that simulate biological processes, and she and Henzinger argued that such computer-based research could not only help scientists make sense of complexity, it would bring a precise, formal, quantifiable approach to the life sciences. “A computerized model begins with a hypothesis. When you organize the experimental results in the same formal language as the model, you can compare the two and immediately see the gaps. These gaps then enable you to refine your model and design new experiments,” she says.

As Fisher was finishing her work with Henzinger, Microsoft Research in Cambridge was adding biology to its list of computational research subjects. Fisher was invited to join the Programming Principles and Tools group there, and was later offered a position as a research group head at Cambridge University.
 
Nowadays, Fisher engages in long-term collaborations with experimental groups to continue investigating cell decision-making processes. In one of those collaborations, she works on understanding how blood cell development goes awry in leukemia. In another, she investigates cell signaling in C. elegans – research that has implications for understanding cancer.  This signaling has been preserved throughout evolution, up to and including humans. Recent findings in her group demonstrated the benefits of repeated cycles of computational modeling, prediction and experimentation. They revealed a crucial molecular mechanism by which developing cells synchronize their cell cycles and then break that synchrony to continue developing toward individual cell fates.

Eventually, says Fisher, her group and others working in the field will produce a broad, common platform for computational biology, and its tools will become standard in the life sciences – akin to the use of microscopes and DNA sequencing equipment today.

Though her rise in the field has taken her out of the country for over a decade, Fisher, a seventh-generation Israeli, admits it has been hard to be away. “The Weizmann Institute still feels like home to me,” she says. Conducting research there has always been a source of pride for me.”
Dr. Jasmin Fisher
Math & Computer Science
English

3D Molecules and a Baby

English

 

 

Dr. Yechun Xu, You-Yang and Dr. Minjun Li. Made at the Institute
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
When Yechun Xu held her newborn daughter You-Yang for the first time, she felt happy and hopeful, as do new mothers everywhere. Her husband Minjun Li, standing nearby, was happy too. The only thing missing was the chance to share their joy with the family members they had left behind in China, their homeland. The staff of the Kaplan Hospital in Rehovot did their best to make them feel at home; so did their friends and colleagues from the laboratory of Prof. Joel Sussman at the Weizmann Institute of Science, who went out of their way to play the role of extended family.

“I felt almost like a grandfather when You-Yang was born,” recalls Sussman, a member of Weizmann’s Structural Biology Department.

Sussman  first met Yechun at the Chinese Academy of Science’s Shanghai Institute of Materia Medica, where she was a doctoral student. Sussman and Weizmann colleague Prof. Israel Silman collaborated with Yechun’s Shanghai Institute mentors on a study of Huperzine A, an herb extract used in Chinese folk medicine. In July 2005, after Yechun obtained her Ph.D., the Israeli scientists invited her to conduct postdoctoral research at the Weizmann Institute. Working under the guidance of Sussman and Silman, she and colleagues solved the three-dimensional structure of different crystal forms of the enzyme BACE1, and of the complexes it forms with an inhibitor. BACE1 is involved in the formation of plaques in the brain that are characteristic of Alzheimer’s disease. As reported in their paper in Acta Crystallographica D Biological Crystallography, this study might help design future anti-Alzheimer drugs.

Meanwhile, Yechun’s husband, engineer Minjun Li (they had met when both were undergraduate students in chemistry at the East China Normal University in Shanghai) had also decided to study abroad. He quit his job with an international company specializing in magnetic resonance equipment and enrolled in a Ph.D. program at the University of Texas.
 
A detailed 3D structure of a new molecular probe (bottom), in complex with the binding site of the estrogen receptor, designed for detecting this receptor as part of an improved method for the diagnosis and treatment of breast cancer
 
But after a year in Houston, Minjun decided to move to Israel, where he could pursue his interest in biology while working side by side with his wife. That was how in the summer of 2006, when an interesting Ph.D. project was offered to him at Weizmann, Minjun joined his wife in Rehovot.

Minjun’s Ph.D. research – conducted under the joint guidance of Sussman and Prof. Hadassa Degani of the Biological Regulation Department – centered on a small molecule designed to target estrogen receptors. As the scientists reported in the Journal of Medicinal Chemistry, this molecule may in the future be used to treat breast cancer and other disorders in which estrogen receptors are overactive; it might also be used in the diagnosis of these diseases, serving as a biomarker for making certain abnormalities more easily visible in magnetic resonance imaging scans. The researchers crystallized the complex formed by the new molecule with the receptor’s binding site and solved its three-dimensional structure. “Knowing the structure may help design compounds with improved properties,” Minjun said in an interview before departing for Shanghai.
 
Plans for the Future
 
Summing up his stay at Weizmann, Minjun said he had greatly appreciated the way in which the Institute facilitates interdisciplinary research: “Weizmann has an open, informal atmosphere in which it’s very easy to communicate with people from other labs and departments.” He added that he found it especially useful to consult researchers involved in the compilation of Proteopedia (http://www.proteopedia.org), a collaborative 3D encyclopedia of proteins and other molecules developed at Weizmann by the Israel Structural Proteomics Center.

The time Minjun and Yechun spent at the Institute was also fruitful in areas outside of research: Yechun gave birth to You-Yang (known as Yo-Yo) in March of 2009. While Minjun stayed on to complete his Ph.D., Yechun and You-Yang moved back to China, so that Yechun could take up her new position at the Shanghai Institute of Materia Medica, as head of her own lab. Minjun followed at the end of 2011 after passing his Ph.D. exam. His plans for the future: to look for a research position, preferably in one of the international pharmaceutical companies that have recently been establishing research branches in China.

While Minjun and Yechun spent most their time on the Weizmann Institute campus enjoying the peaceful surroundings that allowed them to focus on research, they did tour Israel on weekends, visiting historic sites and geographical highlights – particularly the Dead Sea, a landmark all Chinese students learn about in high school. On one occasion, Minjun organized an informal seminar that brought several dozen Chinese students to Weizmann from other Israeli institutions of higher learning. Such gatherings are held by the Chinese student community in Israel about twice a year – usually at Weizmann – and like the previous seminars, this one focused on a variety of topics ranging from education, history and politics to practical matters.

The young Chinese couple praised the warm attitude of their research supervisors at Weizmann, who often invited them to their homes. “They were more like parents than bosses,” said Minjun.
 
 
Dr. Yechun Xu, You-Yang and Dr. Minjun Li. Made at the Institute
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Lasers and Fiber Optics

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(l-r) Dr. Henry Yaffe and Prof. Israel Bar-Joseph in the late 1980s. Laser lab

 
Dr. Henry Yaffe remembers his years at the Weizmann Institute as a series of firsts: “I bought my first new car, married my first wife, bought my first house and my first child was born,” he says. “The wife and child are still with me.” Yaffe, who conducted research the guidance of under Profs. Asher Friesem and Yehiam Prior, also built the first picosecond laser at the Institute.

Before coming to the Institute, Yaffe had been working at Bell Labs in New Jersey. In those days, he says, there was a regular exchange of people and ideas between Bell Labs and the Weizmann Institute, and after a few years, he was persuaded to come to the Institute. He arrived in 1984, first earning an M.Sc. in Friesem’s lab. Then, after working in Institute labs for a year while Prior was on sabbatical, Yaffe began carrying out his Ph.D. research on non-linear optics under the two professors jointly.

“My lab was in the basement of the physics building,” he recalls. “Periodically, the lawn sprinkler system would flood the lab through a ventilation shaft. Each time, we had to carry out expensive repairs.” Happier memories include co-founding the Institute’s first Ultimate Frisbee team (a tradition that continues today) and his wedding to Amit at Weizmann House on the Institute campus in 1987.

Yaffe’s family back home got in on the act as well: His mother and father, Linda and Seymour, set up a chapter of the American Committee for the Weizmann Institute of Science in their hometown, Baltimore, and raised funds for research. “I was probably the only student whose mother paid for his lab equipment,” he quips.

After completing his Ph.D., Yaffe returned to Bell Labs to conduct postdoctoral research and then went to work for CIENA, a telecommunications start-up. In 1999, he left to found his own company, Yafo Networks, which manufactured high-end telecommunications equipment for fiber-optic networks. However, the telecommunications bubble that many companies had been riding burst, and Yafo Networks went down with it. In 2003, Yaffe purchased some of the technology and started another company, called New Ridge Technologies. The devices he now designs and manufactures are used to test and verify the performance of fiber-optic equipment before it is deployed in the network.

“I went from running a large company to a relatively small one,” says Yaffe, “but the Weizmann connection remains. Two years ago I hired a Weizmann grad – Yaniv Barad, a former student of Prof. Yaron Silberberg.”
 
 
(l-r) Dr. Henry Yaffe and Prof. Israel Bar-Joseph in the late 1980s. Laser lab
Space & Physics
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Twins

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Twins: Danit and Einat Finkelshtein
 

 

 
 
While growing up, Danit and Einat Finkelshtein wondered how they’d come to be born identical twins. It’s not that they minded being twins, on the contrary. But they were curious. They queried their mother, a nurse by profession, about the phenomenon of twin births and its genetic origins. “This opened for us a window on science in general, and biology in particular,” Einat says. She and Danit became interested in the human body, especially molecular genetics.

Danit and Einat are best friends; in school, they were in the same class from 9th grade. Though today they make sure not to wear identical clothes, they dress in much the same style. They have many friends in common, go swimming together and enjoy joint outings. It was only natural that after finishing their army service, both enrolled in university studies in biology. Both then embarked upon master’s studies at the Weizmann Institute of Science, and now both are busy working on their Ph.D.s. Unsurprisingly, they study in the same department, that of Molecular Genetics. But here their paths have diverged somewhat. Danit, who is in the group of Prof. Menachem Rubinstein, conducts her research on mechanisms by which viruses enter cells. Einat’s research under the guidance of Prof. Ari Elson focuses on cells that break down bone tissue.
 
 
Twins: Efrat and Reut Shema
Reut and Efrat Shema are also identical twins, but for a number of years they followed different paths in their lives. When their family moved from Rehovot to Moshav Sitriya, Reut decided to stay in her school in Rehovot while Efrat opted for a local moshav high school. After their army service, Reut earned a B.Sc. in brain research and psychology at Tel Aviv University while Efrat studied biology at the Hebrew University of Jerusalem. But when it came to graduate studies, their paths met again: both enrolled in the Weizmann Institute of Science. Today, both are working on their doctorates. Reut studies long-term memory under the guidance of Prof. Yadin Dudai. Efrat’s research, in the lab of her supervisor, Prof. Moshe Oren, focuses on gene regulation and cancer.
 
Reut and Efrat  married in the same year and now live with their families in the same neighborhood in Rehovot. Every day, after picking up their small children from day care, they spend time together.

 
Twins: Asaf and Ido Azuri
 
Identical twins Asaf and Ido Azuri love to discuss science, and they have plenty of opportunity to do so: Both are studying toward a doctorate in the Faculty of Chemistry at the Weizmann Institute of Science. Asaf conducts his research in the group of Prof. Eli Pollak in the Chemical Physics Department, while Ido is with Prof. Leeor Kronik in the Materials and Interfaces Department. Both labs are in the Perlman Chemical Sciences Building, so that to meet for coffee, Asaf and Ido don’t even have to go outside.

This pair did everything together all their lives: spending time with the same friends, enrolling in after-school activities and learning jiu-jitsu and karate (when both reached the finals, they refused to fight each another, preferring to share a joint prize). Science lovers from childhood, both studied exact sciences at Bar-Ilan University: Asaf chose chemistry, while Ido majored in biophysics. Today both study various aspects of theoretical computational chemistry, a field they find rewarding and challenging.
 
Prof. Yadin Dudai's research is supported by the Norman and Helen Asher Center for Human Brain Imaging, which he heads; the Nella and Leon Benoziyo Center for Neurological Diseases; the Carl and Micaela Einhorn-Dominic Institute of Brain Research, which he heads; the Marc Besen and the Pratt Foundation, Australia; Lisa Mierins Smith, Canada; the Abe and Kathryn Selsky Memorial Research Project; and Miel de Botton, UK.  Prof. Dudai is the incumbent of the Sara and Michael Sela Professorial Chair of Neurobiology.
 
Prof. Ari Elson's research is supported by the Ekard Research School of Biological Science, which he heads; the Lorry I. Lokey Research School of Biochemical Science, which he heads; the M.D. Moross Institute for Cancer Research; the Kekst Family Institute for Medical Genetics; the Yeda-Sela Center for Basic Research; the Maurice and Vivienne Wohl Charitable Foundation; the Fritz Thyssen Stiftung; and the estate of Fannie Sherr.  Prof. Elson is the incumbent of the Marshall and Renette Ezralow Professorial Chair.
 
Prof. Leeor Kronik's research is supported by the Carolito Stiftung; the Wolfson Family Charitable Trust; and the Helen and Martin Kimmel Center for Nanoscale Science.
 
Prof. Moshe Oren's research is supported by the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation; the Robert Bosch Foundation; and the estate of Harold Z. Novak.  Prof. Oren is the incumbent of the Andre Lwoff Professorial Chair in Molecular Biology.
 
Prof. Eli Pollak is the incumbent of the Sam and Ayala Zacks Professorial Chair.
 
Prof. Menachem Rubinstein's research is supported by the  estate of Sophie Kalina; the estate of Helena Barkman Schramm; the De Benedetti Foundation-Cherasco 1547; and the Jeanne and Joseph Nissim Foundation for Life Sciences Research.  Prof. Rubinstein is the incumbent of the Maurice and Edna Weiss Professorial Chair of Cytokines Research.


 
 
 
 
 
Danit and Einat Finkelshtein
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