Using an artificial intelligence technique known as deep learning and high-resolution remote sensing, scientists have counted and mapped the location of trees in 11,000 satellite images covering more than 1.3 million square kilometers (500,000 square miles) of the hot dry tropical, arid, and semi-arid western Sahara and Sahel deserts of Mauritania, Senegal, and southwestern Mali. Much to their surprise, the scientists counted 1.8 billion trees—a far greater number than expected based on earlier counts, which had underestimated the number of trees. This study is important in that it established a baseline for future tree counts to aid in the monitoring of how deforestation, global climate change, and perhaps even reforestation are affecting West African ecosystems. See also: Africa; Artificial intelligence; Deforestation; Desert; Ecosystem; Reforestation; Remote sensing; Sahel; Terrestrial ecosystem; Tree; Vegetation and ecosystem mapping

The World Health Organization (WHO) is planning to recognize gaming disorder as a mental health disease in 2018. The 11th revision of the WHO's International Classification of Diseases (ICD), which is a major worldwide reference for epidemiological, clinical, and health-management issues, will include a new listing for a mental health condition termed "gaming disorder," which is related to an individual's overuse of video-game playing. Specifically, this newly classified mental health disorder is characterized by recurrent or persistent gaming behavior in an individual, resulting in the individual's significant impairment in real-life activities and functions, including the deterioration of familial, social, and professional relationships. According to WHO, the condition is manifested particularly by "impaired control over gaming," "increasing priority given to gaming," and "escalation of gaming despite the occurrence of negative consequences." In many ways, gaming disorder will be diagnosed similarly to other addictive disorders. See also: Addiction and addictive disorders; Brain; Computer peripheral devices; Human-computer interaction; Mental disorders; Psychology; Video disk; Video games; Virtual reality

Social media are websites and applications (apps) for content sharing and collaboration among communities of users online. The term encompasses social networks, microblogs, open-content repositories, photo or video sharing, messaging apps, social gaming, and virtual worlds among diverse other offerings. They represent a leading means of communication in the 21st century. Some of the best known social media sites are Facebook, Instagram, Twitter, Tumblr, and Snapchat. Facebook alone has about 1.6 billion active users and Instagram has about 20 billion images. See also: Digital photography; Internet; Virtual reality; Web 2.0 technologies; World Wide Web

Scientists from IBM and Sony Storage Media Solutions Corporation have jointly developed a magnetic storage tape with 20 times the storage capacity (areal density) of currently available tape. The record-setting tape, reported in IEEE Transactions on Magnetics (August 2017), has an areal density of 201 gigabits per square inch. The breakthrough was made possible through advances in tape coating technology, improved read and write heads, and new signal-processing algorithms. Although the tape is currently a prototype, a single cartridge would hold about 330 terabytes of uncompressed data—the equivalent of about 160 million photos two megabytes in size. See also: Computer storage technology; Magnetic recording; Signal processing

The continuing development of quantum computing, a potentially revolutionary form of number-crunching, has reached a new milestone. Earlier this month, IBM announced the building of a prototype 50-qubit processor for the company’s quantum cloud computing platform, IBM Q. This new processor could prove to be a major step—or even the ultimate one—toward “quantum supremacy.” The term refers to quantum computers exceeding conventional computers at certain complex calculations that the latter machines would require impractically long times to perform. See also: Computer; Quantum computation

The flow of pedestrians through public spaces and thoroughfares is frequently a concern of architects, engineers, and planners, as well as building owners and operation managers, who may want to identify potential traffic bottlenecks, reduce congestion, and improve safety. Commercially available pedestrian software models have become highly useful tools for those purposes: They can simulate and graphically present the movement of individuals, small groups of people, and large crowds for analysis. Simulation models do not provide specific answers to pedestrian traffic problems. Instead, they allow users to test various scenarios to see what approaches might work best. For example, a transportation engineer designing a train platform might run simulations for stairway placement to optimize pedestrian clearance times. See also: Architectural engineering; Computer-aided engineering; Computer graphics; Model theory; Railway engineering; Simulation; Software; Transportation engineering

Visitors to websites may think their visits are anonymous, but digital techniques can reveal their identities to site operators and track their movements online more revealingly than they realize. Web fingerprinting, also known as device fingerprinting, machine fingerprinting, or browser fingerprinting, probes web browser and device (computer, smartphone, or tablet) properties, such as screen size, browser plugins, time zones, and system fonts. In most cases, the combination of these properties will be unique and can be used like a fingerprint to identify a user thereafter. (That combination may not necessarily be linked to an individual’s name and full identity, but the user still ceases to be anonymous by becoming recognizable.) Once users are identified, websites can secretly track them. At best web fingerprinting is used for fraud detection by credit card companies and financial institutions, for example. Alternatively, it also is used for analytics, marketing, or for obtaining a user’s entire online history. See also: Internet; World Wide Web