Voyager II image of Neptune, showing storm features. Image: NASA

But wait…What exactly constitutes weather on a giant gas planet? Here on planet Earth, there is a clearly delineated gas layer enveloping the solid/liquid layer we call home. Our weather arises from our planet’s rotation and the solar heating of its surfaces. On a rapidly-rotating gas planet (a day on Neptune is 16 hours long), which receives little warmth from the sun, how do storms arise? Is the whole planet a swirling, turbulent mass, or is the weather confined to an outer layer, like on Earth?

We now have, if not an exact answer, an upper limit for the thickness of weather systems on those planets. And it turns out that they are surprisingly Earth-like (frigid 1000 km/h winds aside): The winds blow in an atmospheric layer that is no more – and probably less – than 1000 km thick. That is much less than one percent of the mass of these planets.

The researchers who calculated this limit – at the Weizmann Institute, Tel Aviv University and the University of Arizona – used slight variations in the gravitational field – gravity maps of the planets – to work out the depth of the weather. On Earth, large masses like mountains slightly increase the planet’s gravitational pull on nearby objects. On gas planets, wind-driven variations in the gas density are what create rises and dips in the gravitational map. By calculating the theoretical gravitational fields on idealized planets of the same size, but lacking winds, and comparing these with the observed gravity, the team was able to ascertain the contribution of wind to the overall pattern.

According to lead author Dr. Yohai Kaspi, having a better grasp of what is occurring on the planets’ surfaces will give us clues to the events taking place deeper within the planets, as well as information leading to theories about their formation and possibly even hints as to the makeup of the many largish exoplanets that have been detected in recent years. Kaspi is on the scientific team of NASA’s Juno mission to Jupiter, and is planning to apply this method sometime around 2016, when the spacecraft will be taking detailed measurements of that planet’s gravity.

So, in that spirit, I offer three haikus, one for each of the new online articles on our site. Among other things, they are proof that a science writer trained to write with word limits can reduce years of demanding research to seventeen syllables. To learn more, follow the links.

A battle between
Immune systems, host, graft
A veto brings peace

Enemies hiding
In a bacterial throng
Exposed by a touch

Non-coding, antisense
Interfering, short and long
Now in one database

Image from the lab of Dr. Guy Shakhar

That question has not yet been definitively answered, but recent research on flying bats shows us what three-dimensional navigation looks like in the brain.

It turns out that fruit bats also mostly navigate in two dimensions, since quite a bit of their flying time involves getting from their caves straight to their favorite fruit trees. But once they get to a tree, they switch to three-dimensional flitting patterns that cover the entire volumetric space around the tree.

To gain some insight into the workings of the bats’ internal mapping system, neurobiologist Dr. Nahum Ulanovsky attempted a feat no one had tried before: seeing into a bats’ brain while it was on the wing. His team spent several years developing a tiny device with electrodes that could measure neuronal activity in the bats’ brains while allowing them to fly naturally. They then let their subjects swoop and dive around some “fruit trees” – poles dangling cups filled with fruit – up inside their oh-so-cool, fully-equipped bat lab.

Image: Dr Yossi Yovel in the lab of Dr. Nachum Ulanovsky, Weizmann Institute of Science

It seems that bat neurons, at least, relate to all three dimensions equally. Their internal maps – as well as ours – are plotted in groups of neurons called place cells. These cells respond to specific locations in the spatial environment. As the bat moves though space, the corresponding place cells send off “you are here” signals. By comparing the bats’ actual locations with the neurons’ signals, the researchers found that each place cell responds to a spherical space – i.e., it has the same resolution in all directions.

Do human place cells map a similar space, or are ours flatter? On the one hand, says Ulanovsky, our nearest relatives probably have place cells very much like those of bats, since they navigate in three-dimensional space through the tree canopy. On the other hand, since we basically walk around in two dimensions, our up-and-down axis may have lost some of its resolution over time, making our internal mapping closer to that of animals that crawl rather than those that fly. This, says Ulanovsky, is a fascinating open question that awaits further experiments.

Goldwasser and Micali’s work in the 1980s laid the foundations of modern cryptography – the science that, among other things, keeps your electronic transactions secure.

The basis of their work is a series of riffs on the concepts of probability and proof. For example, in their seminal “zero-knowledge interactive proofs” paper, they changed, forever, the paradigm of a mathematical proof that must be written down, step-by-step, page after page. Instead, they suggested that a proof can come out of a conversation between two parties – a “prover” and a “verifier.”

Laszlo Lovasz describes it thus:

It sounds paradoxical, but there is a scheme which allows the customer to convince the bank that he knows the password – without giving the slightest hint as to what the password is! ….The most interesting aspect of this scheme is that it extends the notion of a proof, thought (at least in classical mathematics) to be well established for more than 2000 years. In the classical sense, a proof is written down entirely by the author (whom we call the Prover), and then it is verified by the reader (whom we call the Verifier). Here, there is interaction between the Prover and the Verifier: The action taken by the Prover depends on the “questions” of the Verifier.

In other words, by asking a series of questions, each one randomly based on the answer to the previous question, the verifier can ascertain whether the prover has the mathematical proof — without actually learning anything about the proof, itself. Obviously, using a method like this can keep your password from being stolen, but it can also be used by people working together online who want to jointly compute functions without giving away their data.

In fact, Goldwasser and Micali’s work has major implications for the entire field of mathematics known as complexity theory. Lovasz imagines using the method to referee an “exponentially long paper”:

There is a way to write down a proof so that a referee can check the correctness of a theorem by reading only a tiny fraction of it. The proof becomes longer than necessary, but not much longer. The number of characters the referee has to read is only around the logarithm of the original proof length!

Just as important, says Goldwasser, you can use such methods to establish that a mathematical statement is not correct, by proving “non existence” of classical proofs.

Happy International Women’s Day. In the midst of today’s hand wringing about women in science, here’s some good news: The Weizmann Institute has just been awarded a prize by the City of Barcelona for its efforts to promote women in science. Above: Barcelona Civil Rights councilor Francina Vila i Valls presents the award to the Institute’s Dr. Karina Yaniv.

The centerpiece of this effort is the Israel National Postdoctoral Program for Women in Science, which gives grants, on top of the postdoctoral scholarships these women receive, specifically to enable them to move their families abroad for a couple of years.

Aside from this program, the Weizmann Institute somehow manages to combine an intense immersion in scientific research with a family-friendly campus. Many of our researchers live on campus; day-care starts from a young age and the hours are flexible; children are a normal sight on campus grounds, and even in labs (where safety permits, it goes without saying). The women here will tell you this helps, along with a strong group of other women to talk to and who help one another out.

Of course, numbers of men and women professors are still unequal here, as they are everywhere else. Women face the same dilemmas when it comes to family vs career.

On the other hand, there is a wonderful, amazing group of women scientists here who manage to achieve everything their male counterparts do and more while raising families — often just at the point in time when their career is taking off. They include a Nobel laureate, Prof. Ada Yonath,the President of the Israel Academy of Science and the Humanities, Prof. Ruth Arnon, and many others. I never fail to be inspired after talking with one of these women scientists.

So while we continue to strive for more equality in research and academe, I propose we also take a minute to celebrate the achievements of women scientists.

Polyploidy in an adult stem cell. From the lab of Prof. Dov Zipori

What the team discovered – to their great surprise – is that a major change in chromosome number that has been associated with cancer is actually found in stem cells that are less likely to become cancerous. This change is called polyploidy: a multiplication of the entire set of chromosomes such that three, four or even more sets appear in the adult stem cells. Up to now, it has been obvious to everyone that the excess chromosomes in polyploidy can lead to the excess growth of cancer.

When the facts tell a different story, the explanation must change as well, and Zipori has an explanation: Polyploidy may be a cell’s way of avoiding cancer. Adding more genes can dilute the effect of a potentially harmful mutation in one. The fact that some cancer cells are polyploid simply means that the strategy doesn’t always work.

This insight, by the way, led Zipori and his team to a gene that is about a thousand times more active in diploid than polyploid cells. The analysis of this gene turns out to be a good predictor of cancer risk in adult stem cells.

Triple-negative breast cancer cells do have other receptors – particularly EGFR, a growth factor receptor that would seem to be a good target for anticancer antibodies. The problem is that previously tested agents that block EGFR have been found to be ineffective in treating the cancer.

The Weizmann team’s innovation was to go after the EGF receptor with two different antibodies that bound to the receptor from different sides. More than just a one-two punch, the double attack worked better than expected. The scientists think that the weight of the two antibodies on one receptor may not only block it, but cause it to collapse back into the tumor cell.

Breast cancer cell. Image: NCI

All of this, we should point out, worked in mice. Any human studies are well in the future. On the other hand, if the study results are born out, the double-attack approach could prove fruitful for other types of cancer, as well.

Two other news items that went online today:

Researchers discover a star’s “mini-explosion” taking place just a month before an all-out supernova explosion.

A biological device made of DNA inserted into a bacterial cell works like a tiny diagnostic computer.

What happens when a former physics-student-turned-documentary-director is invited to create a video clip for the first ever physics reunion? The answer is below.

You may not learn anything new about physics by watching it, but you will note that Weizmann President Prof. Daniel Zajfman and VP Prof. Israel Bar-Joseph are featured, along with others.

Touching Something No One Found

The Institute’s Prof. Eldad Tzahor had already shown that face and heart go together: Very early on in the developing embryo,  the progenitor cells that will become heart and facial muscles start out together in the same “classroom” – a small area in the neck region. It’s not just incidental: It turns out that these cells not only arise from the same population, they need to “talk” to one another before they can move off to their respective places in the developing embryo.

But this didn’t explain why a single chromosomal deletion can cause a whole range of problems, from relatively mild defects to debilitating ones that require urgent intervention at birth. Tzahor and his student, Itamar Harel began looking for the answer in transcription factors — the proteins that initially control genetic activity.

After identifying a number of relevant transcription factors, Tzahor, Harel and their collaborators around the world spent months developing and testing knockout mice that would reveal, in detail, the functions of these regulatory proteins in the development of the heart and face progenitors. Even more challenging was the creation of double-knock out embryos, missing two of the transcription factors.

Their ultimate finding was that the transcription factors form a network. There are upstream and downstream effects, but also sideways and indirect interactions. And that network tends to be at least partly self- correcting. When two transcriptions factors were lacking, the network’s outputs collapse, but with only one missing, others apparently stepped in to pick up some of the slack, resulting in a few “slip-ups,” but more or less complete hearts and facial muscles.

And yes, they revealed that, at least for those with DiGeorge syndrome, a face can tell something about the heart. They found that knockouts of specific transcription factors that were not previously linked to Digeorge were tied to distinctive combinations of facial muscle and cardiac defects resemble the congenital defects in babies. Tzahor and Harel suggest that certain birth defects in a newborn’s face could tell doctors to check for a corresponding heart problem.

We also wrote about last year’s Fundamental Physics Prizes, handed out by billionaire Yuri Milner. The new Prizes will be officially announced in March, 2013, at CERN.

Our congratulations to Zohar and the other nominees/laureates of these prizes. (In addition to the Fundamental Physics and New Horizons Prizes, Special Fundamental Physics Prizes are being awarded to Stephen Hawking and the leaders of the ATLAS and CMS experiments at the LHC. For more on this year’s prizes go to: http://www.fundamentalphysicsprize.org/news/news3)