In This Issue

doi:10.1073/iti2111108

New Research In

Bright lights reflect big cities, economic development

Nighttime luminosity as an economic indicator.

Many countries in the developing world lack reliable economic statistics, hampering economic policy-making efforts. Xi Chen and William Nordhaus (pp. 8589–8594) explored the usefulness of an intuitive, yet little-known metric as a proxy for economic development: nighttime luminosity, the intensity of nighttime lights such as the slowly brightening lights viewed by passengers on evening flights as a landing aircraft descends toward its destination. Nighttime luminosity for a range of geographic areas has long been measured by satellites. The authors used a modeling approach to compare nighttime luminosity with gross domestic product for an array of countries and regions that had been graded according to the quality of their economic data. The authors found that luminosity could help serve as a proxy for economic output—at both national and regional levels—for countries with little to no statistical reporting systems in place, such as Iraq, Somalia, and Libya. For countries with better quality economic data, such as the United States and Europe, however, luminosity is unlikely to provide valuable economic information, partly because of technical difficulties in the measurement of nighttime lights. Hence, the authors suggest that luminosity could help supplement standard economic indicators in countries with poor economic statistics. — P.N.

International trade can affect emissions

Net emission transfer (black line) via international trade, by sector, between developed and developing countries, 1990–2008.

Many developed countries have reported stable emission levels in recent decades, thanks in part to the accounting rules of the Intergovernmental Panel on Climate Change that require countries to report only territorial emissions. But Glen Peters et al. (pp. 8903–8908) find that international trade could partially account for the disparities in greenhouse gas emissions between developed and developing countries. Between 1990 and 2008, global CO₂ emissions grew 39%, with stable levels in developed countries and rising levels in developing countries with booming economies. To determine whether the disparity in emission levels could be attributed to the increased consumption in developed countries of traded goods produced in developing countries, the authors compiled a trade-linked global database of CO₂ emissions between 1990 and 2008 from 57 economic sectors in 113 countries. The production of traded goods and services, the authors report, accounted for an increase in emissions from 20% of global emissions in 1990 to 26% in 2008. The levels of consumption-driven emissions in most developed countries rose faster than that of territorial emissions. Nonenergy-intensive manufacturing sectors, such as textiles, electronics, furniture, and cars, accounted for a growing share of the emissions due to import from developing countries, according to the authors. — P.N.

Potential alternative to the PSA test

Detecting prostasomes in blood.

The prostate-specific antigen (PSA) test for detecting prostate cancer suffers from a number of shortfalls that call the test's benefits into question. Namely, the test does not always distinguish between relatively benign and aggressive prostate cancer. Nor is the test a foolproof indicator of cancer, largely because PSA levels can soar during inflammation of the prostate gland. Gholamreza Tavoosidana et al. (pp. 8809–8814) explored the use of a different biomarker for prostate cancer: nanometer-sized vesicles, called prostasomes, which ferry life-sustaining molecules from the secretory cells of the prostate gland to developing sperm cells. Whereas prostasomes are normally released into the seminal fluid, the altered tissue architecture of cancer-afflicted prostate glands triggers the release of the vesicles into the space between the secretory cells, and then into the bloodstream. The authors developed a diagnostic blood test based on the recognition of four different proteins on prostasomes using a handful of antibodies to distinguish between individuals with and without prostate cancer. Compared with age-matched controls without cancer, prostate cancer patients, the authors report, showed a two- to seven-fold higher median level of circulating prostasomes in their blood plasma. In addition, the blood prostasome levels reflected the aggressiveness of the cancer, as indicated by a clinical measure of the severity of the patients’ cancer. The findings suggest that prostasomes could serve as a reliable blood biomarker for prostate cancer, according to the authors. — P.N.

Water detoxification using reactive double membranes

Double-membrane system for clean water production.

Access to safe drinking water has been identified as one of the most important challenges of the 21st century. Common groundwater pollutants include chlorophenols such as trichloropropane, a well-known fungicide/pesticide, and chloroethylenes such as trichloroethylene (TCE), a potentially carcinogenic degreasing solvent. Scott Lewis et al. (pp. 8577–8582) designed a double membrane that uses glucose and iron to detoxify water without the need for expensive posttreatment. The researchers stacked two membranes to first generate hydrogen peroxide with glucose, and then to facilitate a reaction between the peroxide and iron ions or particles within the second membrane that created free radicals—reactive molecules that readily break down organic compounds. Traditional additions or subtractions of harmful chemicals are unnecessary because the enzyme and iron are immobilized within the membranes and because the process does not create toxic byproducts, the authors report. To illustrate the membranes’ real world applicability, the researchers mixed iron oxide particles with hydrogen peroxide in a similar reaction to degrade TCE in contaminated groundwater. In the United States, approximately two-thirds of the most serious hazardous waste sites are contaminated with TCE, the authors report. Though the membranes were developed and tested for environmental applications, the authors suggest the membranes could also help kill bacteria or inactivate viruses within the water supply. — J.M.

Imaging cardiac conduction with ultrasound

Ultrasound image of cardiac electromechanical activation.

Abnormalities in cardiac electrical conduction are major causes of death and disability, but diagnosis and treatment are confounded by the lack of noninvasive methods for studying this process. The electrical and mechanical components of cardiac function are usually measured separately, but Jean Provost et al. (pp. 8565–8570) sought to capture and map both components of the short-lived, electrically induced deformations that occur when the heart's electrical activation causes it to contract. In a validation study, the authors show that the electromechanics of all four chambers of the heart can be imaged using an entirely ultrasound-based technology called electromechanical wave imaging (EWI). The authors first revealed that EWI measurements of cardiac electrical activation in dogs agreed with measurements taken by electrodes. The authors then used EWI to noninvasively map electromechanical waves in all four chambers of the human heart. According to the authors, the technique could complement other methods used by cardiologists to diagnose and evaluate treatment of potentially fatal conduction abnormalities resulting from tissue damage. The method should be fairly easy to implement, the authors suggest, because it can be performed using a standard ultrasound machine. — M.L.P.

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