8,670 research outputs found
Twisted split-ring-resonator photonic metamaterial with huge optical activity
Coupled split-ring-resonator metamaterials have previously been shown to
exhibit large coupling effects, which are a prerequisite for obtaining large
effective optical activity. By a suitable lateral arrangement of these building
blocks, we completely eliminate linear birefringence and obtain pure optical
activity and connected circular optical dichroism. Experiments at around
100-THz frequency and corresponding modeling are in good agreement. Rotation
angles of about 30 degrees for 205nm sample thickness are derived.Comment: 6 pages, 4 figure
Convergence Rates for Newton’s Method at Singular Points
If Newton’s method is employed to find a root of a map from a Banach space into itself and the derivative is singular at that root, the convergence of the Newton iterates to the root is linear rather than quadratic. In this paper we give a detailed analysis of the linear convergence rates for several types of singular problems. For some of these problems we describe modifications of Newton’s method which will restore quadratic convergence
Weyl node with random vector potential
We study Weyl semimetals in the presence of generic disorder, consisting of a
random vector potential as well as a random scalar potential. We derive
renormalization group flow equations to second order in the disorder strength.
These flow equations predict a disorder-induced phase transition between a
pseudo-ballistic weak-disorder phase and a diffusive strong-disorder phase for
sufficiently strong random scalar potential or for a pure three-component
random vector potential. We verify these predictions using a numerical study of
the density of states near the Weyl point and of quantum transport properties
at the Weyl point. In contrast, for a pure single-component random vector
potential the diffusive strong-disorder phase is absent.Comment: published version with minor change
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
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
Corn-boring insects of Iowa: with special reference to the stalk borer, Papaipema Nebris (Gn) and the four-lined borer, Luperina Stipata (Morr)
The biology of the four-lined borer Luperina Stipata (Morr.)
1. The four-lined borer, Luperina stipata (Morr.), is a native insect, normally feeding upon slough grass, but occasionally causing considerable dead heart damage to corn.
2. There is but one generation each year. The overwintering eggs hatch during late April or early May, and after a growing period of from 10 to 14 weeks the larvae pupate. The moths emerge during the fore part of August and deposit eggs for the next year\u27s brood.
3. Quality of food and temperature materially affected the length of larval life of laboratory specimens. Apparently quality of food (succulent versus woody) determined the amount of growth (as measured by the increase in width of successive head capsules) that occurred during a stadium and the number of molts required to complete development. On the other hand temperature determined the rate of development (as measured by the duration of the individual stadia).
4. Natural enemies play an important part in holding this insect in check. The 21 species of parasites and predators are represented by: two Diptera, seven Hymenoptera, four Coleoptera, three Hemiptera, two mammals and three diseases.
5. Borers collected from Spartina were parasitized, but those taken from corn were free from parasites.
6. Elimination of slough grass from fence rows and burning the heavily infested grasslands between Nov. 1 and April 1 are recommended as means of control
An Annotated List of the Crambid Moths Known To Occur in Iowa (Pyralidae, Lepidophera)
For the past fifteen years the writer has been interested in sod webworms and their parents the Crambid moths. During this period\u27 : light trap and field collections have resulted in the building of a. fairly complete collection of the moths of the genus Crambus that are found in Iowa
Insurance Law-Uninsured Motorist Coverage-Insurers Extending Liability Coverage Into Mexico Need Not Provide Coextensive Uninsured Motorist Coverage- Transamerica Insurance Co. v. McKee
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