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packaged it into a safe and compact fiber-optic probe-based system that can be used during routine patient examination. Clinical trials performed in collaboration with researchers at the University of New Mexico Health Science Center and the Albert Einstein College of Medicine in New York compared the fiber-optic system against traditional colposcopy. Initial tests showed that the optical system has similar accuracy for the detection of precancerous lesions to that of well-trained and experienced colposcopists. Presently, Mourant and Los Alamos tech- nologists Oana Marina and Claire Sanders are trying to determine what specific molecular changes within the cell are responsible for the differences in light scattering, and they are looking at the potentially helpful effect of acetic acid. Topical application of acetic acid (the main component of vinegar) often causes cancerous and precancerous cells to visibly whiten and is regularly used during colposcopy. The problem with the acetowhitening-colposcopy system is that it relies on the human eye (the eye of whichever clinician is performing the exam), which permits neither quantification nor standardization. The whitened appearance is actually an increase in the amount of light reflecting from the tissue’s surface, prompting Mourant to speculate that the molecular mech- anism responsible for acetowhitening may also be involved in the light scattering differences exploited by her optical diagnostic system. If they can determine which cellular elements are scattering the most light, and whether these are the elements that are altered during cancer, they may be able to apply their analysis to other types of tissue and their corresponding cancers. Determining properties of tissue by mea- suring the intensity of light that has passed through it is difficult, because it is hard to know where the light went without already know- ing the detailed structure of the tissue. One approach to this problem is to simulate light transport through tissues with slightly different, predefined properties. To do this, Mourant has teamed up with Jerome Spanier and his team of mathematical modelers at the University of California at Irvine to develop computational methods to simulate light passing through different types of tissues. By bringing together cellular systems, optical systems, mathematical modeling, and high- performance computing, this technology will improve both the clinical experience and the accuracy of diagnosis. Moving forward, Mourant sees this work being relevant to many other questions in cancer biology. “Using fiber optics to look at the insides of people is not new to medicine. But we are not just looking, we are diagnosing. And that is new and very exciting,” she says. In fact, the diagnostic power of fiber optics is also being investigated by other research groups studying colon and esophogeal cancers, which frequently reach late-stage disease before diagnosis, have high mortality rates, and cost billions annually to treat. Indeed, just as high-speed communi- cation and other modern conveniences have benefitted from fiber optics, so too may certain essentials of health and longevity. tarballs. These can have either a warming or cooling effect on climate, depending on whether they absorb or scatter sunlight, but are not normally taken into account in climate models because they aren’t considered signifi- cant. The team expected to see some tarballs in their analysis, but they saw a lot— in fact, —Eleanor Hutterer the tarballs were the dominant type of particle. Another surprise was that there were two kinds of tarballs—dark and bright—visible in the Warming by Wildfire? electron microscopy images. The team, which included Claudio Mazzoleni of Michigan Techno- Here’s the thing about predicting the logical University (formerly a Los Alamos Direc- climate: it’s all based on models. Models are tor’s postdoctoral fellow mentored by Dubey), built with the pieces you have, and you need found that dark tarballs, which comprise about the right pieces to get the right prediction. a third of the tarballs examined, are more highly According to Los Alamos climate scientist and oxidized than bright tarballs. Highly oxidized emissions expert Manvendra Dubey, the models organics like these are more efficient than less- currently being used to simulate and predict oxidized organics in taking up water to become climate change may not have all the right pieces cloud drops—the tiny droplets of water that when it comes to wildfires. largely make up a cloud. By increasing the When the record-breaking Las Conchas number, size and concentration of these drops megafire came to Los Alamos’s doorstep in June within a cloud, the presence of dark tarballs, of 2011, Dubey saw an opportunity for discov- counterintuitively, makes the cloud reflect more ery. The town had been evacuated at the peak sunlight, resulting in a cooling effect. of the threat, but once the fire was reduced to Dubey also found another surprise in the a smolder and the evacuation order was lifted, Las Conchas fire emissions analysis, this one Dubey and his team hurried to deploy aerosol involving soot particles—small spherical par- emissions sensors. They wanted to know what ticles of black carbon that aggregate together kind of carbon particles were in the air after in chain-like clumps. Most of the soot particles such a large, hot fire. The size and shape of the examined were coated with other organic com- collected particles were examined by electron pounds from the fire—compounds that focus microscopy, and the results were startling. sunlight, resulting in a warming effect. This The majority of collected particles were means that soot particles, which are treated as amorphous, spherical carbon particles called bare in most climate models, are being modeled The probe used during a clinical exam for fiber-optic detection of cervical cancer is about 3 millimeters in diameter. 28 1663 April 2014 False-color scanning electron micrograph showing aerosol particulates collected from Los Alamos after the Las Conchas megafire in 2011. Three types of carbon particles are shown: climate-cooling dark tarballs (green), climate-warming bright tarballs (soft yellow), and an aggregated clump of organic-coated soot particles (pink).