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Menlo Park, CA, United States

SRI International , founded as Stanford Research Institute, is an American nonprofit research institute headquartered in Menlo Park, California. The trustees of Stanford University established SRI in 1946 as a center of innovation to support economic development in the region. The institute formally separated from Stanford University in 1970 and became known as SRI International in 1977. SRI describes its mission as discovery and the application of science and technology for knowledge, commerce, prosperity, and peace. It performs client-sponsored research and development for government agencies, commercial businesses, and private foundations. It also licenses its technologies, forms strategic partnerships, sells products, and creates spin-off companies.SRI's annual revenue in 2013 was approximately $540 million. SRI's headquarters are located near the Stanford University campus. William A. Jeffrey has served as SRI's president and CEO since September 2014.SRI employs about 2,300 people. Sarnoff Corporation, a wholly owned subsidiary of SRI since 1988, was fully integrated into SRI in January 2011.SRI's focus areas include biomedical science, chemistry and materials, computing, Earth and space systems, economic development, education and learning, energy and environmental technology, security and national defense, as well as sensing and devices. SRI has received more than 4,000 patents and patent applications worldwide. Wikipedia.

Yu Z.G.,SRI International
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We present a detailed analysis of spin-orbit coupling (SOC) in π-conjugated organic materials and its effects on spin characteristics including the spin-relaxation time, spin-diffusion length, and g factor. While π electrons are responsible for low-energy electrical and optical processes in π-conjugated organic solids, σ electrons must be explicitly included to properly describe the SOC. The SOC mixes up- and down-spin states and, in the context of spintronics, can be quantified by an admixture parameter in the electron and hole polaron states in π-conjugated organics. Molecular geometry fluctuations such as ring torsion, which are common in soft organic materials and may depend on sample preparation, are found to have a strong effect on the spin mixing. The SOC-induced spin mixing leads to spin flips as polarons hop from one molecule to another, giving rise to spin relaxation and diffusion, which are examined by the time-dependent perturbation theory and density-matrix theory. The spin-relaxation rate is found to be proportional to the carrier hopping rate, or equivalently, carrier mobility. The spin-diffusion length depends on the spin mixing and hopping distance but is insensitive to the carrier mobility. An applied electric field causes spin drift and gives rise to upstream and downstream spin-diffusion lengths in the hopping-conduction regime. The SOC influences the g factor of the polaron state and makes it deviate from the free-electron value. The deviation is due to the mixing of different orbitals in the polaron state, which does not include the spin mixing within the same orbital, and therefore underestimates the SOC strength. In particular, the g factor is not sensitive to the molecular geometry fluctuations, where the spin mixing within the same orbital is dominant. The SOCs in tris-(8-hydroxyquinoline) aluminum (Alq 3) and in copper phthalocyanine (CuPc) are particularly strong, due to the orthogonal arrangement of the three ligands in the former and Cu 3d orbitals in the latter. The theory quantitatively explains the recent measured spin-diffusion lengths in Alq 3 from muon spin rotation and in CuPc from spin-polarized two-photon photoemission. © 2012 American Physical Society.

Denning D.E.,SRI International
Proceedings - IEEE Symposium on Security and Privacy | Year: 2012

Disclosure of classified data in multilevel database systems is threatened by direct user access, user inference, Trojan Horse release, and Trojan Horse leaks. Earlier work showed how the problems of direct user access and Trojan Horse release can be solved by using a trusted filter and cryptographic checksums, but left the problems of inference and leaks open. We now show how the problem of user inference can be solved with the concept of a commutative filter that ensures that the result returned to a user is equivalent to one that would have been obtained had the query been posed against an authorized view of the database. The technique allows query selections, some projections, query optimization, and subquery handling to be performed by the database system. It does not solve the Trojan Horse leakage problem. © 1985 IEEE.

Rohlfing T.,SRI International
IEEE Transactions on Medical Imaging | Year: 2012

The accuracy of nonrigid image registrations is commonly approximated using surrogate measures such as tissue label overlap scores, image similarity, image difference, or transformation inverse consistency error. This paper provides experimental evidence that these measures, even when used in combination, cannot distinguish accurate from inaccurate registrations. To this end, we introduce a registration algorithm that generates highly inaccurate image transformations, yet performs extremely well in terms of the surrogate measures. Of the tested criteria, only overlap scores of localized anatomical regions reliably distinguish reasonable from inaccurate registrations, whereas image similarity and tissue overlap do not. We conclude that tissue overlap and image similarity, whether used alone or together, do not provide valid evidence for accurate registrations and should thus not be reported or accepted as such. © 2011 IEEE.

Denning D.E.,SRI International
Proceedings - IEEE Symposium on Security and Privacy | Year: 2012

A model of a real-time intrusion-detection expert system capable of detecting break-ins, penetrations, and other forms of computer abuse is described. The model is based on the hypothesis that security violations can be detected by monitoring a system's audit records for abnormal patterns of system usage. The model includes profiles for representing the behavior of subjects with respect to objects in terms of metrics and statistical models, and rules for acquiring knowledge about this behavior from audit records and for detecting anomalous behavior. The model is independent of any particular system, application environment, system vulnerability, or type of intrusion, thereby providing a framework for a general-purpose intrusion-detection expert system. © 1986 IEEE.

Tsunoda R.T.,SRI International
Geophysical Research Letters | Year: 2010

Interpretation of the morphology of equatorial spread F (ESF) is usually given in terms of factors that modulate the growth rate of the Rayleigh-Taylor instability. That interpretation is, however, incomplete because only one means for growth-rate enhancement has been included; that is, the strength of the post-sunset rise of the F layer could become enhanced, when the solar terminator aligns with geomagnetic field lines. Maxima in ESF occurrence observed near equinoxes seem accountable by this means, but maxima observed near solstices require another source of enhancement. Seasonal migration and latitudinal alignment of the inter-tropical convergence zone (ITCZ) with the magnetic dip equator is suggested as the missing source, and shown able to fill that void. Copyright © 2010 by the American Geophysical Union.

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