Welch Wanderings continued

Dr. Irizarry's Opus

When he was a child growing up in Puerto Rico and taking his first tentative plinks at the family piano, Rafael Irizarry could not have known that his budding love for music would one day steer him toward a career as a biostatistician in public health.

By the time he entered college, Irizarry had mastered a whole batch of instruments — the guitar, piano, and cuatro, as well as the conga and bongo drums. And even though he majored in math, he never forsook his first love: He was still playing rhythm for Latin street bands around San Francisco when he entered Berkeley's PhD program in statistics.

So it was natural, when it came time to pick a dissertation subject and his PhD advisor asked him about his interests, that Irizarry quickly answered "music." His advisor suggested he report to the university's Center for New Music and Audio Technology (CNMAT).

Irizarry, an assistant professor of Biostatistics at the School, remembers thinking at the time, "This is not really smart, doing statistics on music. Is this a professional dead end?" But he went ahead in spite of his misgivings.

Researchers at the CNMAT gave him some recorded music and asked him to try separating the music's harmonic sounds from the nonharmonic. The harmonic parts of a musical note consist of faint overtones layered at precise intervals one on top of another above the actual note. This mix of overtones is one part of timbre, the characteristic sound of a particular musical instrument.

 Irizarry worried that mixing his talent for statistics with his love of music would be a "professional dead end." He charged ahead anyway.

But timbre is also formed by the nonharmonic parts of sounds: a calloused finger scraping over a guitar's steel-wound strings, the rasp of a bow against a cello string, saliva moving through the innards of a horn. "These nonharmonic sounds have no pitch or tone," explains Irizarry. "They're what in statistics we call noise, but that's a pejorative term. They are actually crucial to an instrument's sound. If you take this 'noise' out of a guitar recording, for instance, what's left won't sound like a guitar because it won't have the pluck, the nonharmonic part."

At CNMAT, Irizarry used statistical methods to turn musical sounds into zeros and ones and then, using a computer, learned how to siphon off the nonharmonic "noise" as he broke down the music into its constituent parts (a process called decomposing).

The residuals he was collecting were much in demand by young composers at CNMAT looking for new sounds to work with. But besides piquing the interest of avant-garde composers, Irizarry's sorties into musical decomposition steered him into a field of statistics known as time series, which in turn led him to public health.

Unlike the haphazard samples of observations that most statisticians analyze, time series are non-random, consecutive measurements collected at equally spaced time intervals. Long used in astronomy and physics, time series are now of importance to the biomedical sciences because new technologies are allowing researchers to measure over time such things as fetal heart rates, brain waves, circadian rhythms, and the interactions between vast numbers of genes.

But in order for these immense quantities of data to be useful, someone has to figure out how to manage and analyze them. To Irizarry, these cascades of data are like miles-long melodies. "Lots of things in nature are close to being periodic," he notes. "From what I've learned from music, I can use similar techniques to work with measurements of brain signals, say, or pollution levels over time." He pauses, then adds, "I am discovering music everywhere at the School of Public Health."

Rod Graham

Pop the Cork!

It was a good spring for Dean Alfred Sommer.

Within a period of a few weeks last May, the School received an anonymous \$100 million gift to combat malaria; two stellar population experts agreed to join the senior faculty; and Sommer, MD, MHS '73, became one of the few people in School history to be elected to the National Academy of Sciences (NAS).

Created by the U.S. Congress in 1863 to advise the government in scientific and technical matters, the National Academy of Sciences is the nation's most prestigious scientific organization. The Academy currently has 1,900 active members and 300 foreign associates, of whom 170 have won Nobel Prizes. New members are elected each April in recognition of their distinguished and continuing achievements in original research.

NAS members have traditionally come from the ranks of experts in the most fundamental of the sciences: cosmic physics, computational biology, structural chemistry. But, as Sommer understands it, his electors wanted in particular to expand the Academy's representation to physician-scientists and others in fields beyond the molecular sciences. "Since there's never been an ophthalmologist or an epidemiologist or a biostatistician elected to the NAS before, it's a pretty good guess that my work with vitamin A played a role," he says.

 "Since there's never been an ophthalmologist or an epidemiologist or a biostatistician elected to the NAS before, it's a good guess that my work with vitamin A played a role."

The dean was able to choose which NAS section he wanted to belong to, and selected Medical Physiology and Metabolism. "There were no sections having to do with public health or epidemiology," he says, "and very few that have to do with physicians or physician-scientists." His goals as a NAS member? "My major agenda will be to try and recognize people in the population sciences like epidemiology and biostatistics. For me it provides an opportunity to bring our sciences to the table and get more people recognized."

As it turns out, there was more good news for the dean. About two weeks after learning of his election to the NAS, Sommer got a call from France notifying him that he was to receive the Danone International Prize for Nutrition Research at the August 30 International Congress of Nutrition in Vienna. And a few days after that, he was told that in October he would receive the Bristol-Myers Squibb/Mead Johnson Award for Distinguished Nutrition Research.

And all these good tidings came on top of W. Harry Feinstone's surprise \$3 million gift last October, which endowed the chairmanship of the W. Harry Feinstone Department of Molecular Microbiology and Immunology in the name of Sommer and his wife Jill.

Says Sommer, "It's interesting how things seem to happen in clusters for no particularly apparent reason — but we're always pleased when that happens."

RG

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