Seeing in the Blind Spot

Every driver knows—or should know—about the “blind spot,” that part of the road that you just can’t see in any of your car’s rear-view mirrors, the spot that all too often hides a semi-tractor trailer full of hazardous wastes passing you at 70 miles an hour on a crowded turnpike.

R. Andrew Hicks, an associate professor of mathematics at Drexel University, has a better solution than a quick turn of the head and a yelp of surprise. He has created a slightly and elegantly curved mirror that provides drivers with a 45 degree field of view on the driver’s side. A flat mirror provides less than 20 degrees. The difference is dramatic.

Flat mirrors do not provide a wide enough field of view. Trucks and buses make use of spherical mirrors, which broaden the field, but increase the distortion of the image. The passenger-side mirror on a car, the one with the worrisome note that “objects in the mirror may be closer than they appear,” also trades a wider field for a distorted view.

Hicks has been working on creating very wide fields of view, in the new field of “omnidirectional vision,” sometimes also called panoramic vision, which has been developed to help robots to “see.” A mobile robot might use a camera with an extremely wide-angle “fish-eye” lens or with curved mirrors mounted in front of a standard lens. Omnidirectional vision provides a very large field of view.

Curved mirrors can provide the same kind of panoramic views—such as often seen in CCTV security cameras. Hicks was designing such mirrors for robots as a postdoctoral fellow at the General Robotics, Automation, Sensing, and Perception Laboratory at the University of Pennsylvania, where he received a Ph.D. in mathematics in 1995. He also was learning a lot about the problems of building them. The theoretical design of a curved mirror that has a wide and undistorted view is a “problem of classical optics,” Hicks says. That elegantly drawn curve, however, was until recently impossible to translate into a physical mirror. “The tricky part is that the machines that could actually build a practical design didn’t exist before 2000. So nobody really explored making such a mirror.”

Hicks can now make and demonstrate such a mirror, but he can’t sell it: U.S. law prohibits a curved mirror on the driver’s side. (It is allowed in Europe and Japan and as an add-on in the U.S.) Until that can be changed, he still advocates, as your driver-ed teacher did, an occasional quick glance over the shoulder.

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18th-Century Architecture: 21st-Century Technology

All the students in the Digital Media Program at the Antoinette Westphal College of Media Arts and Design learn how to create the latest in computer graphics and animations. But the students working at Independence National Historical Park with Glen Muschio, the director of the program, are also getting a crash course in American history. Philadelphia may be America's most historic city, but much of what the tourist sees has been reconstructed over the centuries. Drexel University researchers are beginning to uncover what 18^th-century Philadelphia was really like—and to create an interactive computer model of it that anyone can explore. Muschio, Chris Redmann, assistant professor of digital media and their students have been recreating exact 3-D replicas of colonial-era structures. The project brings together faculty and students from the computer science department in the College of Engineering, the culture and communication department in the College of Arts and Sciences, the College of Information Science and Technology and the School of Education.

The collaborative 3-D Colonial Philadelphia
will serve as a research and production center for models, animations and interactive media—a repository for "virtual artifacts" of colonial life, in searchable databases for researchers and scholars. The Dexter House was recreated based on information regarding the house foundation obtained at the site and a survey of buildings from the time period fitting the style of the house and buildings created by the Dexter House's carpenter.

"We want this to be a resource for research, production, use and evaluation of digital assets for studying U.S. history," says Muschio. The project is part Second Life, part social history, part SimCity, part computer science and part teaching tool. "What we hope to do is create a 3-D environment for teaching and learning about colonial American history in schools, at historic sites and on the Web" he adds.

One of the first homes recreated in their virtual 18^th-century Philadelphia is a two-story brick house located in the vicinity of Fifth and Arch Streets that belonged to James Oronoko Dexter, a prominent and free African-American. Dexter is believed to have held meetings at his house for the creation of the first independent African American church. The original house was demolished in the 19^th century, but recent archeological digs brought to light information about the house and site.

Muschio and his students have built the exterior and interior spaces of the home with historical accuracy and will scan artifacts found from the dig to restore the interior to its 18^th- century look. Another building, the Whitall House, home of wealthy Quakers, which still stands in Woodbury, N.J. opposite Philadelphia International Airport, has been another model.

The future of the project includes regional sites and events that were historically significant to the development of the city's culture and economics. "3-D Colonial Philadelphia will evolve as technology advances and as we too develop cutting- edge technology to move the field forward," says Muschio. He wants to recreate the 18th-century city and its economic ecosystem, eventually populating its buildings with digitized characters, or avatars, who will show visitors the objects found there, and tell them about the significance of the site—like virtual tour guides. "As AI [artificial intelligence] capabilities develop, we hope that the interaction will get to the state where we can really do this on a big scale and people can get involved in role-playing games. That's where we're headed. Right now, were building the spaces in a photo-realistic way."

"We are working with the computer science department, which is interested in creating algorithms that will allow them to work with the National Park Service to virtually reconstruct the Dexter artifacts, based on the remnants that were uncovered," said Muschio. "We're also working with information-science technology to create databases so we can get a handle on all of this stuff, because we hope to make this available to other researchers in other cities who might not have the types of resources we have in terms of window types, brick face, things like that."

Chris Redmann, an architect and 3-D animator with an interest in historic preservation, is directing the construction of the 3-D virtual environments. He's teaching his undergraduate and graduate students to use the Historic American Building Survey (HABS) and the Historic American Engineering Record (HAER) as guides for reconstructing 3-D models of historic buildings. These digital assets will be used to construct virtual period buildings that are known to have stood on specific plots, but are undocumented in terms of detailed descriptions. The faculty and students will also research insurance, tax and deed records noting physical descriptions and positioning of structures.

The resulting database of colonial Philadelphia doors, windows, brick faces and other common features could be dropped into a scene or a row of houses quickly. Whole blocks, which might have sketchy historical records at best, could then be recreated with some measure of authenticity.

Working from HABS blueprints, undergraduate student Brian Gadomski, has already built an archive of 18th-century house doors and windows. "I'm bringing them into 3-D and I'm tracing them in the computer, and building, based on the original drawing, a geometry that matches exactly with those," he says. "It's a process that's relatively simple but will allow us to create a data base of doors and windows that can be used eventually in the complete Colonial Philadelphia."

"Using this method, it will not be possible to know what every specific house in the city looked like," said Muschio. "Detailed treatments will be reserved for historically significant structures that are well documented."

"I actually learned a lot about the Dexter house while doing it," said Chester Cunanan, a graduate student in digital media. "How they had the first meetings there that eventually led to the first African American church in Philadelphia and how the Quakers worked with that."Cunanan says that he has learned more than he expected. "You have to learn about the history of the place to build the place properly, and then the history catches you at that point. So when it starts, maybe you weren't totally into the history, but when it ends, you're not only interested in the place, but the history and the place. The history pushes you on—it's the impetus that drives you after the fun of playing with a new toy wears off."

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The Mysteries of Autism

The definition of an epidemic is simple, but subjective, warns Craig Newschaffer, professor and chairman of the department of epidemiology and biostatistics at the Drexel University School of Public Health: "An epidemic means that there are more cases of a disease than we would expect." He cites the example of smallpox, an affliction for which a single confirmed case would qualify as an epidemic, because the disease has been eliminated in humans. On the other hand, when everybody you know has a cold, that's to be expected, and therefore not an epidemic.

What about autism? In the last 20 years the number of reported cases has gone up—everyone agrees. But has autism increased more than expected? Are we in the midst of an autism epidemic?

It's hard to tell, for many reasons, and Newschaffer, to the dismay of many a reporter looking for a sound bite that answers the question, knows them all. ""For one thing," Newschaffer notes, "autism isn't one thing. It's a spectrum of disorders." That means different and perhaps unknown causes, risk factors, and genetic predispositions.

Might the increase in autism be due to improved diagnostics, that is, to children who would previously have been diagnosed with mental retardation or learning disabilities today being diagnosed with autism? Experts debate the issue. Parents worry that there's "something out there" causing autism.

"There are two major hypotheses," Newschaffer says. "One is that something is going on that increases children's risk of autism. The other is that the increased number of cases is due to changes in the autism diagnosis and an increased tendency to diagnose autism instead of something else."

What causes autism? "Like cancer, autism is a very complex disease," says Newschaffer, "and it's exciting to start asking questions about the interaction between genes and environment. There's really a very rich array of potential exposure variables."

Newschaffer says we don't know the cause of autism. That means autism diagnosis has to be made on the basis of behavior rather than biology—and that's the always unpredictable behavior of a child we're looking at. And studies that look back at the infant behavior of older children, before the disease was well-known, simply aren't a sharp enough tool to unearth, once and for all, whether autism was as common in the past as it is now.

There strong beliefs on both the "nature" and "nurture" sides of the issue," Newschaffer says. "But if you try to get objective and sit back –if you try to be honest –I don't think the data are valid, precise, or good enough to tease these things out." But "we need to consider environmental risk factors."

Many new studies are in progress. But Newschaffer doubts that a definitive answer will be found soon. "We are not likely to develop a conclusive body of evidence to either fully support or fully refute the notion that there has been some real increase in autism risk over the past two decades," he says.

In a 2005 study, Newschaffer and his colleagues concluded that shifting diagnostic categories alone can't account for the increase in autism cases. Newschaffer's data suggested some increase in autism cases. "Saying that it's an epidemic is a powerful word," he reminds us—it means more public attention and funding.

After the release of data from the Centers for Disease Control and Prevention (CDC) on autism prevalence in the spring of 2007, Newschaffer was invited to speak to the Congressional Caucus on Autism Research and Education to offer his expert opinion on the new data from the CDC autism and developmental disabilities monitoring (ADDM) project. The project indicates that almost seven in 1,000 8-year-old children had an autism spectrum disorder. The data, collected across multiple project sites nationwide, represents the best available estimate of the prevalence of autism in the United States. Fourteen ADDM project sites are established across the nation, including sites in Pennsylvania, New Jersey and Maryland. Newschaffer, who joined the faculty of the School of Public Health this past fall, was one of the first ADDM project principal investigators and remains affiliated with the Maryland ADDM project site.

Newschaffer stresses the importance of identifying common symptoms within the wide variety of autism spectrum disorders, as well as ways to better observe genes and the environment together. He also notes that several federally funded epidemiological studies are underway to pinpoint possible environmental triggers for autism, including an initiative by the CDC. Newschaffer serves as co-principal investigator of this CDC study, which is expected to review 2,700 children over the next five years.

He's working on an interesting new study, working at Drexel's 11^th Street Clinic with mothers of autistic children—a "high-risk cohort—"who are now pregnant again. "The benefit of early identification is immeasurable," he says, although he does "hope to measure it." "We need to get the word out to families." He says that starting out at birth with a child at risk of autism offers the best hope that he might find the biomarkers for autism. "The richest samples" for biomarkers, he says, are in the placenta. "What genes are expressed by the baby in the womb?" he asks. The whole first year of the project, the year he's in now, calls for recruitment and outreach. "We're not rushing into data collection," he notes. "If you don't have a lot of data, you're not doing science."This is not treatment research."

The ultimate goal for Newschaffer and his colleagues is a comprehensive collection of all the available about the disease: the National Database for Autism Research NDAR (http://ndar.nih.gov/ ) "Adding to some body of knowledge: that's the goal. We're in public health," Newschaffer says, "to prevent mobility and mortality from diseases. A "cure" is really tertiary prevention—in public health we're really into primary prevention: stopping disease before it happens."

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Professor and chairman of the department of epidemiology and biostatistics at the Drexel University School of Public Health, Newschaffer was recently at the department of epidemiology at the Johns Hopkins Bloomberg School of Public Health. At Johns Hopkins, Newschaffer founded and directed the Center for Autism and Developmental Disabilities Epidemiology, one of five federally funded centers of excellence in autism epidemiology. Major initiatives included the development of methods for monitoring autism spectrum disorders prevalence and participation in the largest population-based epidemiologic study of autism risk factors to date – the National CADDRE Study of Autism and Child Development. Dr. Newschaffer also is engaged in other projects focusing on how particular genes might interact with environment exposures to increase autism risk. His recently began a collaboration with Peking University to explore approaches for conducting epidemiologic research on autism in China. Newschaffer is an Associate Editor of the American Journal of Epidemiology, and a member of the editorial board of the journal, Developmental Epidemiology.

 

The Badger Game: Colored Amazons

African-American women make up about a half of the women incarcerated in the United States, and are the fastest growing population in today’s jails and prisons.

Kali N. Gross, an assistant professor of history and the director of the Africana Studies Program in the College of Arts and Sciences, knows that the problem isn’t new: its long and troubling history offers insight into the volatile mix of race and gender in American society. She has been studying the history of the crimes and imprisonment of black women in Philadelphia after the Civil War and recently published Colored Amazons: Crime, Violence, and Black Women in the City of Brotherly Love, 1880-1910 (Duke University Press, 2006).

Gross reconstructs the crimes committed by, and attributed to, black women, as well as their portrayal in the popular press and in the pamphlets and speeches of urban and penal reformers. She considers what these crimes signified about the experiences, ambitions and frustrations of these marginalized women. The perpetrators and the state, Gross argues, jointly constructed black female crime. For some women, crime functioned as a means to attain personal and social autonomy. For the state, black female crime justified a host of urban reform initiatives that reaffirmed white, middle-class authority.

Providing an overview of Philadelphia’s incarcerated black women, she also describes their work, housing and leisure activities and their social position in relation to the city’s native-born whites, European immigrants, and elite and middle-class African Americans. She relates how news accounts exaggerated black female crime, trading in sensationalistic portraits of threatening “colored Amazons,” and she considers criminologists’ interpretations of the women’s criminal acts, interpretations largely based on racist notions of hereditary criminality. Gross contends that the history of black female criminals is in many ways a history of the rift between the political rhetoric of democracy and the legal and social realities of those marginalized by its failures.

To write the history of black women criminals at the end of the 19^th century, Gross had to grapple with problematic and challenging primary sources. When black women appeared in the pages of the Philadelphia newspapers, the eroticized horror stories of “Black Amazons” on the rampage offered titillation for contemporary readers. These accounts provide Gross today with a historical record that reveals much about the racism of the courts and the press of the times, but little about the people themselves. And yet: “If they didn’t have criminal records these women wouldn’t show up at all” in the historical record, Gross says.

The historian’s work is to interpret such difficult data. Gross’s research methods involved painstaking close reading of an astonishing array of materials: Statistics, scandal rags, prison records, official trial transcripts, news accounts, and occasional mug-shots are the raw material of Gross’s research. Her work is especially persuasive because she has the statistics to demonstrate racist court practices. The numbers of black people in prison far outweighed their numbers in Philadelphia, and black women faced the most discrimination, evident in the large number of them incarcerated.

In addition to statistics, Gross says her narrative reveals the ways in which “criminal acts and courtroom and prison behavior were also expressive acts—they were texts to be read,” for a deeper understanding of the women’s motivations and their social context. “I use the criminal records and the crimes themselves as texts,” she says. “Badger theft,” as Gross reads it, “is a crime that speaks volumes about frustration and rage.” “The badger game” was a trick that an enterprising black woman might employ against a white man: she would lure him into an out-of-the-way nook with a promise of prostitution, and then rob him before the act. Most often, the shame of having solicited a black woman prevented the victim from pressing charges. If he did, he would be the butt of ridicule in court. Gross infers that many cases of this crime must therefore have gone unrecorded.

It was a dangerous game. The risk of death was always present, as it was in the lives of all black men and women of Philadelphia at that time. The crimes she describes are often shockingly violent; Gross wanted to know, “How did these women learn to be so violent?” Black Philadelphia was a place where crime was often a way for the powerless to assert some control over their lives—Gross refers to a “tropic of violence.” Black women not only reflected a violent environment, they often had to turn to violent crime to establish any agency in a racist and sexist society. But she resists turning them into romanticized rebels.

In the course of her research, Gross learned to appreciate the efforts of these black women to take some place in a society that excluded them. One accused thief wrote a letter to the court—a rare case where we have the actual words of a black woman,” says Gross—that she was “trying to enjoy the rights of my citizenship.” Many of these women were freed slaves or the children of slaves. Gross says that when she had completed her research, she “was actually shocked that there wasn’t more crime.”

While noted for its Quaker tolerance, “Philadelphia had its own brand of racism,” Gross says. She demonstrates the obvious difference in tone in two accounts of the same crime in two Philadelphia newspapers, one of which thought the assailant was black, the other white. Was the weapon, as the Inquirer reported, “a large pocket-knife,” “plunged into the back” ? Or was it a “small knife that she happened to have in her hands,” as the Times-Philadelphia reporter, who thought she was white, wrote?

She spent hours poring over crumbling newspapers, fading photographs and dry prison records but Gross recalls that her scholarly exploration of black women in prison didn’t begin in any dusty archive. “This book began behind bars,” she says, “when I team-taught a seminar to female inmates at the State Correctional Institution in Muncy, Pennsylvania in 1999,” while she was working on Ph.D. in history at the University of Pennsylvania. “I wanted to us my expertise as a historian to educate and empower these women,” but she found that was “telling uplifting tales of noble suffering and perseverance—themes that dominate much of African-American history—to women who, by those accounts, would be thought failures.”Colored Amazons was a way to tell their story. Gross is unequivocal about why she does it. “The subject of black female criminality merits much more scholarly attention—from historians and politicians too.”

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Gross has an extensive background in the study of race and crime and also in the experience of blacks in the U.S., the Caribbean, and in South America. She received a B.A. degree in Africana Studies from Cornell University and an M.A. and Ph.D. in American Civilization and History from the University of Pennsylvania and has been the recipient of numerous awards and fellowships, some of the most notable being a Ford Postdoctoral Fellowship hosted at Princeton University, a postdoctoral fellowship at the Schomburg Center for Research in Black Culture in New York City, and the Letitia Woods Brown Memorial Prize, presented by the Association of Black Women Historians.

Cheap Concrete from Ancient Egypt

When you take on the sole survivor of the Seven Wonders of the Ancient World, the modern world takes notice. Michel Barsoum never sought fame as an Egyptologist, and whenever the Drexel material scientist tells the story of how he helped reveal the ancient secret of the construction of the pyramids, he starts by insisting, “This is not my day job.”

Barsoum helped prove the theory that the pyramids were partially constructed of concrete. Not content with that intriguing possibility, Barsoum charged ahead to investigate how the ancient Egyptians could have made concrete, millennia before its “invention” by the Romans. “How energy intensive or complicated can a 4,500 year old technology really be?” Barsoum asks. The answer, he reports, is that “it is not very complex or costly” and thus, may be useful even today.

Barsoum and his team have invented—or re-invented—an inexpensive, environmentally sustainable and widely available building material: the kind of concrete he thinks the pyramid builders used. What makes Barsoum most proud is the potential practical application of the “geopolymer” that he and his team have reconstructed. A “chance” discovery about the ancient world, made by an engaged engineer, has the potential to help solve some of the environmental and economic problems that vex the world today.

In 2001 Barsoum took a cold call from a friend of a retired colleague, who wanted to know how much Barsoum knew about “the mysteries of the Great Pyramids of Giza.” Barsoum was born in Egypt and has a bachelor’s degree in materials engineering from the American University in Cairo, but didn’t know much about the construction of the famous monuments.

Conventional wisdom offered a familiar image: thousands of slaves hauling carved limestone blocks up ramps hundreds of meters long. But in 1982 a French researcher had suggested that the stones of the pyramids were actually made of a very early form of concrete created using a mixture of limestone, clay, lime and water.

“It was at this point in the conversation that I burst out laughing,” recalls Barsoum. If the pyramids were indeed cast in concrete, not stacked blocks of stone, he says, it could be proved with just a few hours of modern electron microscopy of the structure of the materials.

It hadn’t been tried. Barsoum, who says today that “stubbornness” is one of the important qualities a good researcher needs, decided to try it, and “What started as a two-hour project turned into a five-year odyssey with one of my graduate students, Adrish Ganguly, and a colleague in France.”

Barsoum and the team analyzed the mineralogy of parts of the Khufu pyramid and found mineral ratios unknown in naturally occurring limestone sources. From the geochemical mix of lime, diatomaceous earth and limestone aggregate, they concluded, “the simplest explanation” would be that it was cast concrete. Construction with limestone concrete could help explain how the Egyptians were able to complete such massive monuments so long ago. They used concrete blocks, Barsoum said, on the outer and inner casings and probably on the upper levels, where it would have been difficult to hoist carved stone.

“The sophistication and endurance of this ancient concrete technology is simply astounding,” Dr. Barsoum wrote in a report in the December 2006 issue of The Journal of the American Ceramic Society. John Noble Wilford wrote in The New York Times that “This would be the earliest known application of concrete technology, some 2,500 years before the Romans started using it widely in harbors, amphitheaters and other architecture.”

It isn’t its aura of romantic adventure and ancient mystery that excites Barsoum about this research. It’s much more practical. After all, he says, “At the end of the day, we may be wrong about the pyramids. Nature is very resourceful. What I know for sure is that we are now making this geopolymer. And the ingredients are simply dirt, dirt, dirt and water.”

When he mentions “dirt, dirt, dirt and water” Barsoum’s eyes light up. The import of such a simple recipe for such an extraordinary material also is firing the imagination of his engineering students from freshmen to seniors. Barsoum says, “This ancient variety of concrete can be made just about anywhere in the world from readily available materials, at a very low cost, and without producing the pollution of traditional methods.”

It’s easy to make. Barsoum’s undergraduates work with it all the time: he keeps a cast representation of a cat in his office, and it’s beautiful: as smooth and shiny as marble. The possibilities for housing, transportation and infrastructure, in places that where energy and money are limited, are limitless.

“The basic raw materials used for this early form of concrete--limestone, lime and diatomaceous earth—can be found just about anywhere.” Barsoum quickly adds that this simple construction method would be cost effective, long lasting, and much more environmentally friendly than the current building material of choice. It’s estimated that the manufacture of Portland cement puts 6 billion tons of CO₂ annually into the atmosphere. The ancient Egyptian method is practically pollution-free.

“Ironically it turns out the study of these four thousand year old rocks,” Barsoum says, “isn’t about the past, it’s about the future of the planet.”

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Barsoum, Distinguished Professor in the Department of Materials Science and Engineering, received the Drexel University Research/Scholarship Award in 2007 for the discovery of the kinking nonelastic deformation, a fully reversible deformation mode which is observed in a wide range of materials including geological materials, ceramic materials, graphite and hexagonal metals. This discovery is expected to have major ramifications for the development of new high damping, high strength and high toughness structural materials.