Archives: 07/2016

Elevated CO2 Stimulates the Growth of Papaya

Papayas are spherical or pear-shaped fruits known for their delicious taste and sunlit color of the tropics. Upon his arrival to the New World, Christopher Columbus apparently could not get enough of this exotic fruit, reportedly referring to it as the “the fruit of angels.” And the fruit of angels it may indeed be, as modern science has confirmed its value as a rich source of important vitamins, antioxidants and other health-promoting substances to the consumer.

Papaya production has increased significantly over the past few years to the point that it is now ranked fourth in total tropical fruit production after bananas, oranges and mango. It is an important export in many developing countries and provides a livelihood for thousands of people. It should come as no surprise, therefore, that scientists have become interested in how this important food crop might respond to increasing levels of atmospheric CO2 that are predicted for the future.

Such interest was the focus of a recent paper published in the scientific journal Scientia Horticulturae by Cruz et al. (2016). Therein, the team of five researchers examined “the effect of the elevated CO2 levels and its interaction with Nitrogen (N) on the growth, gas exchange, and N use efficiency (NUE) of papaya seedlings,” as they note there are no publications examining such for this species to date. To accomplish their objective, Cruz et al. grew Tainung #1 F1 Hybrid papaya seeds in 3.5 L plastic pots in a climate-controlled greenhouse at the USDA-ARS Crops Research Laboratory in Fort Collins, Colorado under two different CO2 concentrations (390 or 750 parts per million) and two separate N levels (8 mM NO3- or 3 mM NO3-). CO2 fumigation was performed for only 12 hours per day (during the day, 06:00 h to 18:00 h) and N treatments were applied to the pots weekly as a nutrient solution to reach the desired N levels. The experiment concluded 62 days after treatment initiation.

In discussing their findings, Cruz et al. report that compared to ambient levels of CO2, elevated CO2 increased photosynthesis by 24 and 31 percent in the low and high N treatments, respectively. Plant height, stem diameter and leaf area in the high N treatment were also enhanced by 15.4, 14.0 and 26.8 percent, respectively, and by similar amounts for the height and stem diameter in the low N treatment. Elevated CO2 also increased the biomass of leaf, stem plus petiole, and root dry mass of papaya plants regardless of N treatment, leading to total dry mass enhancements of 56.6 percent in the high N treatments and 64.1 percent in the low N treatments (see figure below).

Figure 1. Total dry mass of papaya plants grown in controlled chambers at two different CO2 concentrations (High and Low; 750 and 390 ppm) and two different N treatments (High and Low; 8 mM NO3- or 3 mM NO3-). Adapted from Cruz et al. (2016).

Figure 1. Total dry mass of papaya plants grown in controlled chambers at two different CO2 concentrations (High and Low; 750 and 390 ppm) and two different N treatments (High and Low; 8 mM NO3- or 3 mM NO3-). Adapted from Cruz et al. (2016).

 

Cruz et al. also report that “significant, but minor, differences were observed in total N content (leaf plus stem + petiole plus roots) between plants grown at different CO2 concentrations, but the same N levels.” Consequently, plant Nitrogen Use Efficiency (NUE) – the amount of carbon fixed per N unit – was around 40 percent greater in the CO2-enriched environments, regardless of the N level in the soil.

Commenting on their findings, Cruz et al. write that contrary to some other studies, which have suggested that low N reduces plant responses to increased CO2 levels, they found no such decline. In fact, their data indicate that elevated CO2 “alleviated the effect of low N on dry matter accumulation in papaya,” which they surmised is at least partially explained by a larger leaf area and higher rate of photosynthesis per leaf area unit observed under elevated CO2.

In light of all of the above, Cruz et al. conclude that “an increase in the atmospheric CO2 concentration [is] beneficial for dry mass production of papaya and alleviate[s] the negative effects of N reduction in the substrate on papaya growth.” Thus, in the future, those who cultivate this fruit of angels should find an angel in the ongoing rise in atmospheric CO2.

 

Reference

Cruz, J.L., Alves, A.A.C., LeCain, D.R., Ellis, D.D. and Morgan, J.A. 2016. Interactive effects between nitrogen fertilization and elevated CO2 on growth and gas exchange of papaya seedlings. Scientia Horticulturae 202: 32-40.

What We Know About Fatal Tesla Accident

Numerous media stories have reported the first fatality in a self-driving car. The most important thing to know is that the Tesla that was involved in the crash was not a self-driving car, that is, a car that “performs all safety-critical functions for the entire trip” or even a car in which “the driver can fully cede control of all safety-critical functions in certain conditions” (otherwise known as “level 4” and “level 3” cars in the National Highway Traffic Safety Administration’s classification of automated cars). 

Instead, the Tesla was equipped with an Advanced Driver Assistance System (ADAS) that performs some steering and speed functions but still requires continuous driver monitoring. In the NHTSA’s classification, it was a “level 2” car, meaning it automated “at least two primary control functions,” in this case, adaptive cruise control (controlling speeds to avoid hitting vehicles in front) and lane centering (steering within the stripes). BMW, Mercedes, and other manufacturers also offer cars with these functions, the difference being that the other cars do not allow drivers to take their hands off the wheel for more than a few seconds while the Tesla does. This may have given some Tesla drivers the impression that their car was a level 3 vehicle that could fully take over “all safety-critical functions in certain conditions.”

The next most important thing to know about the crash is that the Florida Highway Patrol’s initial accident report blamed the accident on the truck driver’s failure to yield the right-of-way to the Tesla. When making a left turn from the eastbound lanes of the highway, the truck should have yielded to the westbound Tesla. Still, it is possible if not likely that the accident would not have happened if the vehicle’s driver had been paying full attention to the road.

Mobileye, the company that made the radar system used in the Tesla, says that its system is designed only to prevent a car from rear-ending slower-moving vehicles, not to keep them from hitting vehicles laterally crossing the car’s path. Even if the sensors had detected the truck, automatic braking systems typically can come to a full stop only if the vehicle is traveling no more than 30 miles per hour faster than the object. Since the road in question is marked for 65 miles per hour, the system could not have stopped the Tesla.

Thus, the Tesla driver who was killed in the accident, Joshua Brown, probably should have been paying more attention. There are conflicting reports about whether Brown was speeding or was watching a movie at the the time of the accident. Neither were mentioned in the preliminary accident report, but even if true it doesn’t change the fact that the Tesla had the right of way over the truck.

Just two months before the accident, Duke University roboticist Missy Cummings presciently testified before Congress that auto companies were “rushing to market” before self-driving cars are ready, and “someone is going to die.” She didn’t mention Tesla by name, but since that is so far the only car company that allows American drivers to take their hands off the wheel for more than a few seconds, she may have had it in mind.

Tesla’s autopilot system relies on two forward-facing sensors: a non-stereo camera and radar. Tests by a Tesla owner have shown that the system using these sensors will not always stop a vehicle from hitting obstacles in the road. By comparison, the Mercedes and BMW systems use a stereo camera (which can more quickly detect approaching obstacles) and five radar sensors (which can detect different kinds of obstacles over a wider range). Thus, in allowing drivers to take hands off the steering wheel, Tesla may have oversold its cars’ capabilities.

The day before information about the Tesla accident became publicly known, the National Association of City Transportation Officials issued a policy statement about self-driving cars urging, among other things, that drivers not be allowed to use “partially automated vehicles” except on limited access freeways because “such vehicles have been shown to encourage unsafe driving behavior.” While this would have prevented the Tesla crash, it ignores the possibility that partial automation might have net safety benefits overall.

A few days after the accident became publicly known, NHTSA announced that traffic fatalities had increased by 7.7 percent in 2015, the largest increase in many years. As Tesla CEO Elon Musk somewhat defensively pointed out, partial automation can probably cut fatalities in half, and full automation is likely to cut them in half again. State and federal regulators should not allow one accident in an ADAS-equipped car to color their judgments about true self-driving cars that are still under development.

We Don’t Need More Border Patrol

Trump’s call for a wall along the border reflects a common desire to control that supposedly lawless frontier.  As far as unauthorized immigration goes, the border is coming under increasing control.  337,117 total unauthorized immigrants were apprehended by Border Patrol in 2015, the lowest number since 1971 (Chart 1).  That number will likely rise this year but will still remain low.  

Chart 1

Border Patrol Apprehensions

 

Source: Customs and Border Protection.

Like the rest of government, Border Patrol has grown considerably over the decades despite the fall in apprehensions.  In 2015 there were just over 20,000 Border Patrol agents, double the number in 2002 and 6.3 times as many as were employed in 1986 (Chart 2). 

Chart 2

Border Patrol Officers

 

Source: Customs and Border Protection.

The increase in the size of Border Patrol has likely decreased unauthorized immigration, although the precise amount is up for debate (read this excellent report for more information).  On the opposite side, there is consistent evidence that border security does not affect the number of illegal entries but can dissuade migrants from leaving once they make it in.  Although the effect of Border Patrol and security on illegal entries is not entirely clear, it is obvious that the average Border Patrol officer is apprehending fewer unauthorized immigrants than at any time in decades with the exception of 2011 (Chart 3).

Chart 3

Apprehensions Per Border Patrol Agent

Source: Customs and Border Protection.

There is already too much corruption in Customs and Border Protection, exacerbated by rapid expansions in the size of their force.  New hiring binges will likely increase the struggles with corruption still more.  Problems with agency corruption and a low period in unlawful immigration are superb arguments against expanding and perhaps to even shrink the Border Patrol back to a reasonable size.

We’ve Been over the Huge Price of “Free” College before

Hillary Clinton will be introducing a plan today that would enable students from families eventually making up to $125,000 not to have to pay tuition at in-state colleges or universities. This is a jump in college subsidization from her previously announced plan, which focused on debt-free tuition, and more in line with what Bernie Sanders has proposed. Presumably, it is going to be paid for by the federal government offering states more money for higher education in exchange for states saying they’ll increase their own spending, to a point of making tuition largely free.

We’ve been over how costly “free” college really is–massive overconsumption, credential inflation, big opportunity costs for taxpayers, etc.–which you can read about here and here. I won’t rehash it all now. But the political calculus hasn’t changed: People like getting things for free, especially when the ultimate costs are hidden. And the more people who think they’ll benefit–the estimate is 8 out of 10 for Ms. Clinton’s new proposal–the better.

Should Teachers Have to Pay for Gushing over Clinton? (Or Trump? Or Gary Johnson? Or…)?

At just about the same time FBI Director James Comey was discussing how “extremely careless” Hillary Clinton was with classified information during her time as Secretary of State, the president of the National Education Association, the nation’s largest teachers union, was tweeting this:

And this:

And doing this:

All of this, by the way, took place at the NEA’s national convention.

Now, is there anything wrong with a union endorsing and campaigning for a presidential candidate? Heck no! But there is a huge problem when teachers, as a condition of working at government schools, are required to furnish funds for those unions.

I know the response: The “agency fees” teachers in many states are compelled to supply only cover collective bargaining, which is not political. Of course, such bargaining is absolutely political—negotiating with government entities is inherently political—and somtimes coming in at 65 percent or more of full dues, a lot of agency fee money is almost certainly going to more than just collective bargaining and administrative stuff. And money is fungible. Dollars that free payers supply for collective bargaining ultimately frees up other bucks for, I don’t know, maybe straight-out politicking!

Sadly, as you probably know, the U.S. Supreme Court tied up on this 4-4 earlier this year, maintaining a lower court ruling that agency fees are not a violation of constitutional speech and association rights. But just because the Supreme Court stumbled doesn’t mean the political branches of government can’t act to end forced union funding. And from I saw on Twitter yesterday, justice requires that compelled support of unions end.

Why Are Interest Rates So Low?

Since the financial crisis of 2007-09, and especially in recent months, Europe and the United States have seen zero and even slightly negative short-term nominal interest rates, and sub-zero risk-free real interest rates.  In June I participated in a conference on “Zero Interest Rate Policy and Economic Order” at the University of Leipzig, organized by Gunther Schnabl (U Leipzig), Ansgar Belke (U Duisburg-Essen), and Thomas Mayer(Fossback von Storch Research Institute).  The topic faced participants with the need to make a key judgment call: Are ultralow rates the new normal, i.e. are they long-run equilibrium rates determined by market fundamentals, or are they so low because of ultra-easy monetary policies and other policies?  In Wicksell’s terminology, is the real “natural rate” currently below zero, or are central banks holding market rates below the current natural rate? We cannot directly observe the natural rate, but we can look for indirect indicators.

The Constitution Protects Against NIMBYism

It should surprise no one that the government isn’t particularly good at respecting property rights. Still, the Constitution requires that property owners be provided with “due process of law” against arbitrary and unjustified deprivation of their right to put their property to beneficial use. According to several federal appellate courts, however, landowners lack such protections unless they show that they have a statutory “entitlement” to use their land.

This is circular Humpty Dumpty logic. Indeed, that approach impermissibly presumes the legitimacy of restrictions, without considering whether they are lawfully applied.

Most recently, the New York-based U.S. Court of Appeals for the Second Circuit employed the “entitlement” theory to deprive a small developer of its right to upgrade run-down apartment buildings. The NYC Landmarks Commission deprived Stahl York Avenue Company of its property rights by designating these nondescript buildings as landmarks—this despite a previous ruling that these exact buildings lacked any architectural or cultural merit worth preserving.