Proof of Luck: an Efficient Blockchain Consensus Protocol

In the paper, we present designs for multiple blockchain consensus primitives and a novel blockchain system, all based on the use of trusted execution environments (TEEs), such as Intel SGX-enabled CPUs. First, we show how using TEEs for existing proof of work schemes can make mining equitably distributed by preventing the use of ASICs. Next, we extend the design with proof of time and proof of ownership consensus primitives to make mining energy- and time-efficient. Further improving on these designs, we present a blockchain using a proof of luck consensus protocol. Our proof of luck blockchain uses a TEE platform's random number generation to choose a consensus leader, which offers low-latency transaction validation, deterministic confirmation time, negligible energy consumption, and equitably distributed mining. Lastly, we discuss a potential protection against up to a constant number of compromised TEEs.Comment: SysTEX '16, December 12-16, 2016, Trento, Ital

High powered arc electrodes

Nonconsumable metal electric arc electrodes are described capable of being operated in a variety of gases at various pressures, current, and powers. The cathode has a circular annulus tip to spread the emission area for improved cooling

Some Caterpillars Frequently Mistaken for the European Corn Borer

The rapid advance westward of the European corn borer in 1926 has aroused the whole nation, particularly the corn belt states. New infestations were found all thru southern Michigan, across northern Ohio and into six counties in northeastern Indiana. An isolated infestation was discovered in Kankakee County, Illinois, only about 150 miles from Iowa. A number of caterpillars occurring in Iowa are frequently mistaken for the Eropean corn borer. Some of these are of about the saine size and quite similar in color markings and general appear.ance, while others, even tho they are very different in appearance, cause injury which resembles somewhat the work of the European corn borer. This circular is issued . to acquaint farmers and Iowa people in general with the habits and characters of these caterpillars. By careful consideration of the larval descriptions, the time of appearance, and character of the injury, the European corn borer may be distinguished from most of the caterpillars discussed in this circular. The smartweed borer and the lotus borer are exceptions, because they so closely resemble the European corn borer that it requires an expert and a microscope to identify them with certainty

Controlling Screwworms

A new insect pest - the primary screwworm fly - has been moving into Iowa during recent summers to pester and kill some livestock. Two outbreaks were reported in June this year in southern Iowa and more may follow

Rodent pests of Iowa and their control

The destructive rodents which are the subject of this bulletin are ground squirrels, pocket gophers, woodchucks, rats and mice. In addition to the damage done to crops and stored products and injury to livestock, all of these rodent pests, except mice, are frequently responsible for important soil losses. Their burrows are commonly found along slopes, hillsides, ditch banks and road grades where their digging activities loosen and tunnel the ground. Heavy rains on slopes so undermined cause erosion and soil washing (fig. 1). Unless these rodents are controlled, such erosion may render the field unfit for farming. Rats, mice and ground squirrels are abundant in all parts of Iowa. Pocket gophers are well established, particularly in the northern and western parts of the state. Ground hogs are found most frequently in the eastern and southern parts of Iowa, particularly in and near rough, wooded areas

Are Bugs in Your Corn?

During the first two weeks of December a dozen farmers called to find out what they should do to stop stored shelled corn from rotting

The Rare Top Decays t→bW+Zt \to b W^+ Z and t→cW+W−t \to c W^+ W^-

The large value of the top quark mass implies that the rare top decays $t \rightarrow b W^+ Z, s W^+ Z$ and $d W^+ Z$, and $t \rightarrow c W^+ W^-$ and $u W^+ W^-$, are kinematically allowed decays so long as $m_t \ge m_W + m_Z + m_{d_i} \approx 171.5 GeV + m_{d_i}$ or $m_t \ge 2m_W + m_{u,c} \approx 160.6 GeV + m_{u,c}$, respectively. The partial decay widths for these decay modes are calculated in the standard model. The partial widths depend sensitively on the precise value of the top quark mass. The branching ratio for $t\rightarrow b W^+ Z$ is as much as $2 \times 10^{-5}$ for $m_t = 200 GeV$, and could be observable at LHC. The rare decay modes $t \rightarrow c W^+ W^-$ and $u W^+ W^-$ are highly GIM-suppressed, and thus provide a means for testing the GIM mechanism for three generations of quarks in the u, c, t sector.Comment: 19 pages, latex, t->bWZ corrected, previous literature on t->bWZ cited, t->cWW unchange

Change in interplanetary shock acceleration preceding STIP Interval 17

The intensity and frequency of shock acceleration events in the interplanetary medium decreased dramatically in early 1985. Low energy ions were observed by IMP 8 at 1 AU and Voyagers 1 and 2 at 22 and 16 AU, respectively. Voyager 1 was at 25 deg heliographic latitude while IMP 8 and Voyager 2 were near the solar equatorial plane. The decrease in low energy shock events led to a drop in the average ion flux by a factor of 20 to 50. It started about day 10 of 1985 in the approximately .5 MeV channel on IMP8 and took approximately 75 days to reach the new, lower, background level. The decrease at the Voyagers started approximately 50 days later. The time delay between the start of the decrease at IMP and at Voyager 2 implies that decrease was convected outward with a velocity of approximately 535 km/sec. The intensity and frequency of interplanetary shock events remained at the lower level for at least 1.5 years

The European corn borer and its control

In the relatively short time since the European corn borer reached the concentrated corn-growing areas of Illinois and Iowa, the population increase and rate of spread have been greatly accelerated. Its advance across Illinois and deep into Iowa has been from 50 to 100 miles a year. The spread of the borer after its discovery in Clinton County in 1942 is shown in fig. 1. The last few years, which have been exceptionally good corn-growing years, likewise have been good for the borer. Thus, it appears that weather, soil conditions, farming practices and other agricultural factors most favorable for growing large acreages of high-yielding corn are also quite favorable to the borer. As the borer spread into Iowa during 1942 and 1943, its buildup has been most rapid in the counties of more intensive corn production. In general, the borer population is heaviest from Clinton and Scott Counties westward toward the central part of the state. Conversely, the population rise has been much less rapid in those infested counties along the southern and northern borders, where corn-growing conditions are less favorable and the corn acreage much smaller