Las Vegas Blooms in the Desert

Las Vegas is the most arid city in the United States, with less than 4 inches of precipitation per year. Yet it has has bloomed, swelling from a population of just 1,205 people in 1905 to 1.4 million by 2000. There are 5,000 new residents and 1,200 new homes a month. Groundwater alone could not supply the ever-increasing population.

In 1974, Las Vegas began pumping water from the Colorado River for the first time to supply its growing need. By 1985, a return flow credit system had been established, whereby for every liter of purified wastewater Las Vegas returned to the Colorado River, it could withdraw another liter of potable water. Las Vegas lies north of Hoover Dam and Lake Mead, and also several major cities. This makes the quality of Las Vegas’ treated water particularly important. Fortunately, the Southern Nevada Water Authority has gone to great lengths to ensure the water’s quality, and Las Vegas’ water treatment is in the 99th percentile nationwide.

Shane Snyder, who came to speak at Duke, is Research & Development Project Manager for the Southern Nevada Water Authority in Las Vegas. He has spent most of his career investigating pharmaceuticals and endocrine disruptors in water, even testifying before a Senate subcommittee about the risk of pharmaceuticals in water. Water contamination with these compounds is a major issue because many water purification systems are incapable of removing them. This is a major obstacle for water recycling efforts, because hormones and pharmaceuticals can have very adverse effects on humans and wildlife that ingest them.

However, Snyder has led the effort to remove hormones and pharmaceuticals from water, pioneering technologies for effectively removing these contaminants. During the lecture, Snyder discussed the effectiveness of treating water with UV radiation, chlorine, and ozone, among others. He noted that many pharmaceuticals and endocrine disruptors don't disappear with treatment, but transform into other products.

Snyder also recognized that water treatment can require a vast amount of energy. In fact, according to Snyder, 19% of California's energy grid is used to treat water.

“I believe that the future lies in making water treatment efficient and making sure that the public is confident that the water will not be harmful to them or their offspring,” Snyder said.

Putting Digital Meat on the Bones

Ever see one of those cop shows or National Geographic specials where a sculptor turns a tattered old skull into a realistic face?

Today's Visualization Friday Forum was a fascinating tour through the history and future of this exacting art with Andrea Stevenson Won, a medical illustrator and modeler from Raleigh who has done work on prosthetics and museum displays. (she hasn't solved any crimes yet, sorry)

Using intimate knowledge of facial anatomy and some average tissue thicknesses at various landmarks across the face, artists like Won can make an educated guess about a skull's former face. Eyebrows, hair, smirks, etc. get into art, and that's where it can quickly get misleading, she said.

Clay's out -- today it's all done digitally, allowing modelers to do three versions of the same skull, as seen here in this reconstruction of a woman who died in Illinois in the 1840s. Andrea also works with Duke's anaplastology clinic, helping make customized prosthetics for patients who are still very much alive.

Wells would have been proud

In 1897, H.G.Wells wrote a book called 'The Invisible Man'- the first time anyone tried to think rationally about invisibility. But that was just another sort of sci-fi fantasy. Around a century later, we are almost there.

Over the last few years, researchers at Duke and elsewhere have achieved remarkable developments in the effort to make things 'invisible'.

In 2006, researchers in the ECE department at Pratt School of Engineering, in collaboration with Imperial College of London, created a brilliant 'cloak' that deflects passing microwaves and behaves as if it were invisible. This was achieved using metamaterials, which in simple terms, can bend light the unexpected way. They can be modified to produce a negative refractive index. The metamaterials were specifically designed and arranged in circles to interact with electromagnetic waves in a way that natural elements cannot. This is the first breakthrough that highlights the uses of metamaterial technology over electromagnetic properties to create the effect of invisibility.

The following is a video of the working model of the first ever invisibility cloak at Duke, which hides a spherical metal cylinder from microwaves:

Even after this achievement, the researchers were not convinced. There were theories which said that the same theory of invisibility would work for 2-D acoustic cloaks, but not for 3-D, as electromagnetic and sound waves fail to be equivalent in 3 dimensions.

As Steven Cummer, Jeffrey N. Vinik Associate Professor of Electrical and Computer Engineering at Duke's Pratt School of Engineering, said 2 years later , "It was hard for me to imagine that something you could do with electromagnetic waves would be completely undoable for sound waves". So, in 2008, the same team devised a mechanism for another invisibility cloak, this time a 3 D acoustic cloak. Working on the same mathematical model they used 2 years earlier, the team proved that an object can be prevented from reflecting sound waves too.

Building upon all this work, scientists at University of California - Berkeley have conducted studies on metamaterials that can bend light the wrong way in 3 dimensions.

Even though we are far from a War of the Worlds or a Time Machine, in the case of an Invisible Man, there is not much longer we need to wait.

WISE Up about HIV/AIDS

Of all the secondary school students in Africa, only 16% are girls.

To raise this number, Dr. Sherryl Broverman of Duke University and Dr. Rose Odhiambo of Egerton University in Kenya collaborated to found the Women’s Institute for Secondary Education and Research (WISER) in Muhuru Bay, Kenya, an area with some of the highest HIV infection rates in the country. The school is an effort to empower women and help them avoid the cycle of early marriage, early childbirth, HIV, and poverty.

Women, their health and their education, are the heart of all of these issues, says Stephen Lewis, former Canadian ambassador to the United Nations and the UN Secretary-General’s Special Envoy for HIV/AIDS in Africa from 2001 to 2006. He spoke at Duke last week as a guest of Duke’s Global Health Institute as a part of WISER week.

“I believe with every fiber of my being that the single most important battle we face on this planet is the struggle for gender equality,” Lewis said.

In Africa, 61% of people infected with the HIV virus are women. Among 15- to 24-year-olds, almost 80% of those infected are women and girls.


Lewis believes that gender inequality is what puts women at risk for HIV. Because African women lack sexual autonomy, they are not in a position to demand safe sex or use of a condom. As a result, they are very vulnerable to the virus, and also to various kinds of abuse. Hundreds of thousands of women are subject to sexual violence. “The turbulence in the society unleashes male behavior of the worst kind ... There is a tremendous sense of entitlement,” Lewis said. And where there is rape and violence, inevitably, there is HIV.

Even more devastating for many HIV positive women is the inaccessibility of drugs to prevent transmission of the disease to their children. Although certain drugs can reduce the chance of transmission by 50-70%, fewer than a third of pregnant women have access to them. “It’s soul-destroying for these women,” Lewis said.

Of the half-million HIV positive babies born in Africa each year, 50% die before age 2, and 80% die before age 5. “It doesn’t happen in the U.S. or Canada or Europe because we provide a full course of retrovirals [to pregnant women],” Lewis said.

Lewis expressed frustration with the lack of international attention to the issues of AIDS and women’s health in Africa. He cited the United States’ government’s ability to spend $3 billion a week for the war in Iraq, yet barely even $10 billion a year for the war against AIDS.

“I don’t understand the way the world works ... I live my life ricocheting between rage on the one hand and despair on the other.”

However, Lewis is hopeful for the future. He repeatedly praised the efforts of WISER and international NGOs and the progress they’ve been able to achieve around the world. His own NGO, Aids-Free World, promotes urgent and effective international responses to the AIDS crisis by focusing on the achievement of gender equality.