5. War on attrition.. 6. Incoming!

5. War on attrition.

It goes without saying that to be a marine you have to be tough, both physically and mentally. But which is more important? And, more specifically, which is the bigger obstacle to successful training? Working on behalf of America’s marine corps, Leslie Saxon, of the Keck School of Medicine of the University of Southern California, has been trying to find out. The elite of the marine corps is a group called Force Reconnaissance. These troops are employed in special operations, both “green” (in which having had to engage the enemy is deemed a failure) and “black” (where such engagement is the whole point). Initial training to join the force, open only to those already marines or naval doctors, lasts 25 days. Among other things it requires volunteers to tread water for nearly an hour, to run eight miles (12km) while carrying more than 50lb (about 23kg) of equipment, and to swim 100 yards (90 meters) with their hands and feet bound. Only half of those who volunteer for this training complete it. Of those who do not, roughly half are failed by the judges for posing a safety risk or for having a medical problem that stops them completing the course. The other half, though, drop out of their own volition. That high drop-out rate is both expensive and vexing for Force Reconnaissance’s recruiters. They therefore turned to Dr Saxon to find out what is happening, so that they can take steps to reduce the losses. To gather the relevant data, she picked 121trainees and provided each of them with two devices: an iPhone and an Apple Watch (a wrist band that both tells the time like a conventional watch and watches what the wearer gets up to). She loaded the phones with an app that asked participants a range of demographic and psychological questions at the start of their training. From the answers to these she generated, for each volunteer, scores for the five main personality traits recognized by psychologists— openness, conscientiousness, extroversion, agreeableness and neuroticism—and also for ego resilience (ability to control anger and to control impulses when stressed), positive affect (a person’s tendency to experience positive emotions when facing challenges), satisfaction with life and level of psychopathy. The watch, meanwhile, monitored the number of steps its wearer took, and kept track of both heart rate and calorie expenditure. Once volunteers began training, they received further, daily questionnaires on their phones. They were asked to rate their pain, both mental and physical, on a scale of one to five. They were asked if they thought of quitting and if they thought their instructors wanted them to graduate. They were also asked about their sleep, their hydration, their nutrition and their own confidence that they would graduate. Dr Saxon’s sample proved pretty representative in their rates of completion of the course. As she reports in the Journal of Medical Internet Research, 56% were successful, 23% dropped out of their own volition and 21% were removed for a mixture of medical, safety and performance reasons. Analyzing the data for those who dropped out, Dr Saxon found that neither performance on physical standards, such as hikes or aquatic training, nor physiological measures of heartrate, work output, hydration, nutrition and sleep duration predicted who would throw in the towel. Nor, among psychological factors, were conscientiousness, neuroticism, openness or agreeableness relevant. But extroversion (or, rather, introversion) was. Using scores for that parameter and also for positive affect, Dr Saxon was able, retrospectively, topredictwith 70% accuracy who would drop out. She also showed when the towel was most likely to be thrown. A majority of droppings out happened just before a series of timed drills, conducted in a deepwater pool, in full uniform. These drills are designed to test candidates’ ability to perform tasks underwater, holding their breath, in a chaotic environment. What the marine corps’ trainers will do with this information is not yet clear. They could use it to winnow out likely failures before the course starts, though that might seem unfair to introverts who would nevertheless have made it. Or they might choose to identify those who need a bit of encouragement to throw themselves into both the literal and metaphorical deep end, on the presumption that, having done so, they will then take the rest of the course in their stride. Either approach would, presumably, reduce the drop-out rate. What you can be sure of, though, is that the course itself will not be made any easier.  

6. Incoming!

As delivery drones get more common, they may need to protect themselves. Internet shopping makes buying things easier, but has also led to the rise of a new kind of thief: the porch pirate. Porch pirates scour door steps for deliveries that have been made when a householder was out, and nab them. Sometimes, they will stalk delivery vans to do so. Residents of New York City, for example, lose an astonishing 90, 000 parcels every day to porch pirates, according to a report in the New York Times. Porch piracy is a problem that may be solved by the spread of parcel-delivering drones. Because each drone delivery involves a separate journey, rather than having to be fitted into a round, it will be easier for courier and customer to agree on when a drone should arrive than on the arrival time of a van. However, Nirupam Roy and Nakul Garg, a pair of engineers at the University of Maryland, worry that drone deliveries are open to a different sort of piracy—hijacking. A drone in flight is easily upset. A well-aimed stone, baseball or similar missile is enough to bring it down, permitting its payload to be purloined. Nor need such stone-throwers have pecuniary motives. Vandalism, or irritation with the very presence of drones, might also provoke pot shots. High-flying drones, like those employed by the police for surveillance, will normally be out of range of such activity. But parcel drones will have to fly low, at least for part of their journeys. To counter this risk the pair therefore propose to build a lightweight, low-power self-defense mechanism which lets a drone sense a missile fast enough to get out of its way. That is nowhere near as easy as it might sound. Drones are lean machines, provided with only enough battery strength, computing power and payload-carrying capacity to do the job they are designed for. Adding threat-detection measures, such as heavy, power-hungry radar antennae, or spinning lidar units, radar’s optical equivalent, would either reduce range or prevent lift-off in the first place. Dr Roy and Mr. Garg think, however, that they have hit on a low power, lightweight self-defense system suitable for small drones. Instead of employing light or radio waves to detect incoming threats, it harnesses sound waves and the Doppler effect. The Doppler effect is the frequency shift heard as a source of sound approaches or recedes. It is, for example, the reason the pitch of a police siren changes as a patrol car passes in the street. To take advantage of it Dr Roy and Mr. Garg plan to fit drones with diminutive loudspeakers, like those found in smartphones. These would broadcast an ultrasonic tone outward from the drone. Similarly, tiny microphones would then listen for reflections from incoming objects. The Doppler shift of these reflections, run through a bit of on-board processing (but far less than that needed for radar or lidar) would give the bearing of the threat, and thus permit the drone to take evasive action. To test the principle of what they call their Doppler Dodge drone defense system, Dr Roy and Mr. Garg have constructed a static version in their laboratory, and have been throwing objects of various sizes and shapes at it, as if it were a hovering drone. At the moment, it can detect these objects from distances of up to four meters away. That is pretty close, but would still give a drone a tenth of a second’s notice of an incoming missile. This would be sufficient for it to move itself out of the way. Tests on actual drones will take place shortly, and then, if all goes as planned, the two researchers will attempt to extend the system’s range to 30 meters—a reasonable approximation of a stone’s throw.

7. Immortal words.

A rotating panel of historians occasionally ranks America’s presidents. The leading contenders tend to be George Washington and Abraham Lincoln; Lincoln usually wins. The accolade is in part the result of his oratorical brilliance, notably the addresses at Gettysburg and at his second inauguration on March 4th 1865 (a month before Robert E. Lee’s surrender). Together, the two speeches constitute a grand aspirational statement about the meaning of the country’s bloodiest war. Rhetoricians still marvel at Lincoln’s simplicity, authenticity and eloquence. Containing only 700 words (about as many as this review) and lasting under six minutes, the second inaugural was rooted not in utopian expectations of a seamless reunion with the Confederacy, but in the shadow of frightful slaughter on a thousand battlefields. Lincoln (pictured above: look closely) had aged decades in four years. But his faith in democracy and what was right, as he saw them, was firm. Sober and resolute as his nature inclined him, he also embodied what the times required. By 1865 Lincoln had substituted rationalism and fatalism for the predestination theology of his Kentucky forebears at Little Pigeon Creek Baptist Church. But he still venerated the King James Bible and often quoted it at length. Skeptical about the God it depicted, he nonetheless believed that some power beyond human understanding controlled the destiny of nations. As Edward Achorn writes in “Every Drop of Blood”, though Lincoln was hardly an orthodox Christian, his second inaugural was “the most overtly religious” of any presidential speech to that date. He said America’s “original sin” of slavery required a righteous God to purge both those who wielded the whip and the politicians who permitted it. He noted that northerners and southerners read from the same Bible and prayed to the same God, and both invoked God’s judgment on their adversaries. The awful presence he described came from Ezekiel and Jeremiah, not from stories of baby Jesus, meek and mild. But afterwards came divine healing: With malice toward none, with charity to all; with firmness in the right as God gives us to see the right, let us strive on to finish the work we are in; to bind up the nation’s wounds…to do all which may achieve…a just and lasting peace… As they listened, the African-Americans close enough to hear began murmuring, “Bless the Lord, ” the chant growing louder until it erupted into shouts and weeping. America’s partisan newspapers reviewed the address according to their biases. Lincoln’s opponents dismissed it as specious and naive. His allies seemed confused by the biblicism. Ironically, perhaps, the British press—especially the Times, the Saturday Review and the Spectator—applauded the president’s preference for reconciliation over triumphalism. Lincoln’s assassination 41 days later replaced his policy with a “reconstruction” anchored in revenge. Thus, perished a president who, for many Americans, was an almost divine political presence; his magnanimous vision of the nation’s future died with him. Lincoln’s last days have been the subject of more extensive hagiography than for any other president, so it is tempting to dismiss Mr. Achorn’s book, which focuses on the inauguration, as redundant. That would be a mistake. Its strength lies less in the events themselves than in the elaborate detail and rich historical context that he musters. Spring thunderstorms turn the parade route into a muddy quagmire that swallows shoes and ruins dresses. John Wilkes Booth relies on the father of his teenage mistress, a New England senator, for VIP passes to both the inauguration and Ford’s Theatre, giving the murderer more than one chance to get to his victim. Washington’s hospitals overflow with wounded soldiers; prostitutes in its brothels serve the assassin, Confederate agents and federal officials without discrimination. Walt Whitman chronicles the era brilliantly. Freed slaves celebrate jubilantly. As in some of the plays performed in Ford’s Theatre, minor roles sometimes eclipse major ones in this fascinating account. By the end, as well as mourning Lincoln’s fate, American readers might wish for another chance at politics without malice and with charity to all.