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) & Signal. 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.

Quantum information processing using quantum dot spins and cavity QED

Abstract: The electronic spin degrees of freedom in semiconductors typically have decoherence times that are several orders of magnitude longer than other relevant time scales. A solid-state quantum computer based on localized electron spins as qubits is therefore of potential interest. Here, a scheme that realizes controlled interactions between two distant quantum dot spins is proposed. The effective long-range interaction is mediated by the vacuum field of a high finesse microcavity. By using conduction-band-hole Raman transitions induced by classical laser fields and the cavity-mode, parallel controlled-not operations, and arbitrary single qubit rotations can be realized.

Focused crawling: a new approach to topic-specific Web resource discovery

Abstract: The rapid growth of the World-Wide Web poses unprecedented scaling challenges for general-purpose crawlers and search engines In this paper we describe a new hypertext resource discovery system called a Focused Crawler The goal of a focused crawler is to selectively seek out pages that are relevant to a pre-defined set of topics The topics are specified not using keywords, but using exemplary documents Rather than collecting and indexing all accessible Web documents to be able to answer all possible ad-hoc queries, a focused crawler analyzes its crawl boundary to find the links that are likely to be most relevant for the crawl, and avoids irrelevant regions of the Web This leads to significant savings in hardware and network resources, and helps keep the crawl more up-to-date To achieve such goal-directed crawling, we designed two hypertext mining programs that guide our crawler: a classifier that evaluates the relevance of a hypertext document with respect to the focus topics, and a distiller that identifies hypertext nodes that are great access points to many relevant pages within a few links We report on extensive focused-crawling experiments using several topics at different levels of specificity Focused crawling acquires relevant pages steadily while standard crawling quickly loses its way, even though they are started from the same root set Focused crawling is robust against large perturbations in the starting set of URLs It discovers largely overlapping sets of resources in spite of these perturbations It is also capable of exploring out and discovering valuable resources that are dozens of links away from the start set, while carefully pruning the millions of pages that may lie within this same radius Our anecdotes suggest that focused crawling is very effective for building high-quality collections of Web documents on specific topics, using modest desktop hardware © 1999 Published by Elsevier Science BV All rights reserved

Mining quantitative association rules in large relational tables

Abstract: We introduce the problem of mining association rules in large relational tables containing both quantitative and categorical attributes. An example of such an association might be "10% of married people between age 50 and 60 have at least 2 cars". We deal with quantitative attributes by fine-partitioning the values of the attribute and then combining adjacent partitions as necessary. We introduce measures of partial completeness which quantify the information lost due to partitioning. A direct application of this technique can generate too many similar rules. We tackle this problem by using a "greater-than-expected-value" interest measure to identify the interesting rules in the output. We give an algorithm for mining such quantitative association rules. Finally, we describe the results of using this approach on a real-life dataset.

Giant magnetoresistive in soft ferromagnetic multilayers.

Abstract: We show that the in-plane magnetoresistance of sandwiches of uncoupled ferromagnetic (${\mathrm{Ni}}_{81}$${\mathrm{Fe}}_{19}$,${\mathrm{Ni}}_{80}$${\mathrm{Co}}_{20}$,Ni) layers separated by ultrathin nonmagnetic metallic (Cu,Ag,Au) layers is strongly increased when the magnetizations of the two ferromagnetic layers are aligned antiparallel. Using NiFe layers, we report a relative change of resistance of 5.0% in 10 Oe at room temperature. The comparison between different ferromagnetic materials (alloys or pure elements) leads us to emphasize the role of bulk rather than interfacial spin-dependent scattering in these structures, in contrast to Fe/Cr multilayers.

A communal catalogue reveals Earth’s multiscale microbial diversity

Abstract: Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity.