IBM

About: IBM is a company organization based out in Armonk, New York, United States. It is known for research contribution in the topics: Layer (electronics) & Cache. The organization has 134567 authors who have published 253905 publications receiving 7458795 citations. The organization is also known as: International Business Machines Corporation & Big Blue.

The Chemical Structure of a Molecule Resolved by Atomic Force Microscopy

Abstract: Resolving individual atoms has always been the ultimate goal of surface microscopy. The scanning tunneling microscope images atomic-scale features on surfaces, but resolving single atoms within an adsorbed molecule remains a great challenge because the tunneling current is primarily sensitive to the local electron density of states close to the Fermi level. We demonstrate imaging of molecules with unprecedented atomic resolution by probing the short-range chemical forces with use of noncontact atomic force microscopy. The key step is functionalizing the microscope’s tip apex with suitable, atomically well-defined terminations, such as CO molecules. Our experimental findings are corroborated by ab initio density functional theory calculations. Comparison with theory shows that Pauli repulsion is the source of the atomic resolution, whereas van der Waals and electrostatic forces only add a diffuse attractive background.

Exchange-coupled nanocomposite magnets by nanoparticle self-assembly

Abstract: Exchange-spring magnets are nanocomposites that are composed of magnetically hard and soft phases that interact by magnetic exchange coupling. Such systems are promising for advanced permanent magnetic applications, as they have a large energy product--the combination of permanent magnet field and magnetization--compared to traditional, single-phase materials. Conventional techniques, including melt-spinning, mechanical milling and sputtering, have been explored to prepare exchange-spring magnets. However, the requirement that both the hard and soft phases are controlled at the nanometre scale, to ensure efficient exchange coupling, has posed significant preparation challenges. Here we report the fabrication of exchange-coupled nanocomposites using nanoparticle self-assembly. In this approach, both FePt and Fe3O4 particles are incorporated as nanometre-scale building blocks into binary assemblies. Subsequent annealing converts the assembly into FePt-Fe3Pt nanocomposites, where FePt is a magnetically hard phase and Fe3Pt a soft phase. An optimum exchange coupling, and therefore an optimum energy product, can be obtained by independently tuning the size and composition of the individual building blocks. We have produced exchange-coupled isotropic FePt-Fe3Pt nanocomposites with an energy product of 20.1 MG Oe, which exceeds the theoretical limit of 13 MG Oe for non-exchange-coupled isotropic FePt by over 50 per cent.

A security architecture for the Internet protocol

Abstract: In this paper we present the design, rationale, and implementation of a security architecture for protecting the secrecy and integrity of Internet traffic at the Internet Protocol (IP) layer. The design includes three components: (1) a security policy for determining when, where, and how security measures are to be applied; (2) a modular key management protocol, called MKMP, for establishing shared secrets between communicating parties and meta-information prescribed by the security policy; and (3) the IP Security Protocol, as it is being standardized by the Internet Engineering Task Force, for applying security measures using information provided through the key management protocol. Effectively, these three components together allow for the establishment of a secure channel between any two communicating systems over the Internet. This technology is a component of IBM's firewall product and is now being ported to other IBM computer platforms.

Efficiently mining long patterns from databases

Abstract: We present a pattern-mining algorithm that scales roughly linearly in the number of maximal patterns embedded in a database irrespective of the length of the longest pattern. In comparison, previous algorithms based on Apriori scale exponentially with longest pattern length. Experiments on real data show that when the patterns are long, our algorithm is more efficient by an order of magnitude or more.

Interpolation of scattered data: Distance matrices and conditionally positive definite functions

Abstract: Among other things, we prove that multiquadric surface interpolation is always solvable, thereby settling a conjecture of R Franke