Spider

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Spider

See: SPDRs

Spider

Also called a Standard & Poor's Depositary Receipt or a SPDR. An exchange-traded fund that tracks the Standard and Poor's 500. The organization issuing the SPDR owns each of the stocks traded on the S&P 500 in approximate ratio to their market capitalization. SPDR shares can be bought, sold, short-sold, traded on margin; they generally function as if they were stocks. Dividends are paid quarterly and are based on the accumulated dividends of all the stocks represented in the SPDR, less any expenses. Investors use SPDRs (and indeed all exchange-traded funds) as a way to easily diversify their portfolios at relatively low cost. Investors also see the demand for SPDRs as an indicator of which direction the market believes the S&P 500 is going. See also: Mid-Cap SPDR.

spider

References in periodicals archive ?
Implicit boundary conditions in transformation-optics cloaking for electromagnetic waves," Progress In Electromagnetic Research, Vol.
Hao, "Full-wave finite -difference time-domain simulation of electromagnetic cloaking structures," Opt.
There, he worked with Xiang Zhang and other engineers on the idea of "matter cloaking.
The team from Fractal Antenna Systems then conducted a live demonstration of cloaking, making metal pipes disappear over a large microwave bandwidth, with no sensitivity to angular orientation (omni-directionality).
However, Alu said that a much more promising avenue is "active" cloaking technology- designs which rely on electrical power to make objects "vanish".
edu/news/2013/03/26/researchers-create-an-ultrathin-invisibility-cloak/) In a statement , coauthor Andrea Alu said that a metascreen shielding against visible frequencies would be easier to manufacture than other kinds of cloaking devices.
In recent years, the electromagnetic cloaking has attracted increasing attention in the electromagnetic community because it can provide the possibility of reduction of the object's scattering cross section (SCS) from electromagnetic wave impinging on the object [1,2].
However, the PID cloak suggested in [1] has a restriction of large size in the axial direction compared to the cloaked scatterer since the spatial transformation used to design the metamaterial cloaking medium is essentially isotropic (see [1, Eqs.
To overcome this limitation, some new cloaking schemes were developed.
But, for the first time, they've constructed a simple cloaking device that makes itself and something placed inside it invisible to microwaves.
Prof John Pendry, from Imperial College London, said a cloaking material may not take long to develop.