Economist 3/3/16

  1. CRIMINOLOGISTS increasingly rely on “geographic profiling”, an examination of the sites of dastardly deeds that narrows down the possible identities of serial criminals.Dr Le Comber, a biologist, learned of geographic profiling from Kim Rossmo, a criminologist at Texas State University, and reckoned it could be useful for epidemiology, too.Their system, Dirichlet process mixture modelling, is more sophisticated than the criminal geographic targeting (CGT) currently favoured by crime-fighters. CGT is based on a simple assumption: that crimes happen near to where those responsible reside.The Dirichlet model allows for more than one “source”—a place relevant to a suspect such as home, work or a frequent pit stop on a commute—but makes no assumptions about their number; it automatically parses the mess of crime sites into clusters of activity.Through a monumental summing of probabilities across each and every possible combination of sources, the model spits out the most likely ones, with considerable precision—down to 50 metres or so in some cases.
  2. ARGENTINA’S $82 billion sovereign default in 2001 was the largest ever. More than fourteen years later, the country is still cleaning up the mess. On February 29th it agreed to an expensive settlement worth $4.65 billion with four of the largest “holdout” creditors: those who rejected debt restructurings in 2005 and 2010 and instead pursued Argentina for full payment plus interest through the New York courts.During the debt restructurings, 93% of bondholders had agreed to exchange their defaulted bonds for new ones, accepting a haircut of 65%. Unperturbed, the holdouts took their case to Thomas Griesa, a New York judge, who ordered Argentina to pay them in full. Argentina’s government, led by Cristina Fernández de Kirchner, refused. In 2012, in an effort to force Argentina to the negotiating table, Mr Griesa prohibited the country from paying the holders of its restructured debt unless it settled with the holdouts.
  3. But in November last year Argentines narrowly elected Mauricio Macri as president.On February 1st finance ministry officials opened negotiations in New York in an attempt to reach an accord with the remaining holdouts. They made quick progress. On February 2nd a group of Italian bondholders accepted an offer of $1.35 billion. On February 17th two hedge funds, Montreux Capital and EM Ltd settled for for $1.1 billion.Their agreement comes at a cost: the $4.65 billion settlement equates to a write down of just 25%, far more generous terms than were offered to creditors in 2005 and 2010.Mr Macri calculates that this is a price worth paying. His predecessor left Argentina’s economy is in dire straits: in 2015 it ran a 5.8% fiscal deficit; inflation is currently at around 30%. Borrowing on international credit markets will help him to tackle both.
  4. Ethiopia is experiencing its worst drought in decades. Crop production in these regions has dropped by 50% or more in some areas, and failed completely in others. Hundreds of thousands of domestic animals are reckoned to have perished.The rapidly changing skylines of Ethiopia’s modernising cities notwithstanding, about 80% of its population still live off the land.Ethiopia’s present rulers have done much to mitigate the impact. Their Productive Safety Net Programme provides jobs for about 7m people who work on public-infrastructure projects in return for food or cash. There are also a national food reserve and early warning systems throughout theworedas, local-government districts. Ethiopia even managed to accelerate the building of a new railway line—the country’s only one—to bring food supplies from Djibouti on the coast of the Horn of Africa.But the country’s ability to help itself may soon reach its limit. Estimates of the number of people affected by drought doubled between June and October in 2015 to 8.2m, and are now pushing beyond 10m (of a population of about 100m).
  5. MANY prophets of information technology (IT) believe that the next big movement in their field will be the “internet of things”.That, though, will mean putting chips in mundane things like sofa, wallet etc. And those chips will need power, not least to run their communications.Shyam Gollakota and his colleagues at the University of Washington, in Seattle, think they have at least part of an answer to the problem. They propose to reconfigure a chip’s communications so that they need almost no power to work.For a conventional chip to broadcast a Wi-Fi signal requires two things. First, it must generate a narrow-band carrier wave. Then, it must impress upon this wave a digital signal that a receiver can interpret. Following Moore’s law, the components responsible for doing the impressing have become ever more efficient over the past couple of decades. Those generating the carrier wave, however, have not. Dr Gollakota and his team reasoned that it should be possible to separate the jobs of generation and impression. The system they have designed has a central transmitter (which might be built into a Wi-Fi router) that broadcasts a pure carrier wave. Dr Gollakota’s new chips then impress binary data on this carrier wave by either reflecting it (for a one) or absorbing it (for a zero).Not having to generate its own carrier wave reduces a chip’s power consumption ten-thousandfold, for throwing the switch requires only a minuscule amount of current.

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