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.

Analysis of gamma rhythms in the rat hippocampus in vitro and in vivo.

Abstract: 1 We have shown previously, with experimental and computer models, how a ‘40 Hz’ (gamma) oscillation can arise in networks of hippocampal interneurones, involving mutual GABAA-mediated synaptic inhibition and a source of tonic excitatory input Here, we explore implications of this model for some hippocampal network phenomena in the rat in vitro and in vivo 2 A model network was constructed of 1024 CA3 pyramidal cells and 256 interneurones AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid), NMDA (N-methyl-D-aspartate), GABAA and GABAB receptors were simulated on pyramidal cells and on interneurones 3 In both model and experiment, the frequency of network oscillations, in the gamma range, depended upon three parameters: GABAA conductance and decay time constant in interneurone-->interneurone connections, and the driving current to the interneurones 4 The model of gamma rhythm predicts an average zero phase lag between firing of pyramidal cells and interneurones, as observed in the rat hippocampus in vivo The model also reproduces a gamma rhythm whose frequency changes with time, at theta frequency (about 5 Hz) This occurs when there is 5 Hz modulation of a tonic signal to chandelier and basket cells 5 Synchronized bursts can be produced in the model by several means, including partial blockade of GABAA receptors or of AMPA receptors on interneurones, or by augmenting AMPA-mediated EPSCs In all of these cases, the burst can be followed by a ‘tail’ of transiently occurring gamma waves, a phenomenon observed in the hippocampus in vivo following sharp waves This tail occurs in the model because of delayed excitation of the interneurones by the synchronized burst A tail of gamma activity was found after synchronized epileptiform bursts both in the hippocampal slice (CA3 region) and in vivo 6 Our data suggest that gamma-frequency EEG activity arises in the hippocampus when pools of interneurones receive a tonic or slowly varying excitation The frequency of the oscillation depends upon the strength of this excitation and on the parameters regulating the inhibitory coupling between the interneurones The interneurone network output is then imposed upon pyramidal neurones in the form of rhythmic synchronized IPSPs

A logic for reasoning about probabilities

Abstract: A language for reasoning about probability is considered that allows statements such as 'the probability of E/sub 1/ is less than 1/3' and 'the probability of E/sub 1/ is at least twice the probability of E/sub 2/', where E/sub 1/ and E/sub 2/ are arbitrary events. The case is treated in which all events are measurable (i.e. represent measurable sets), as well as the more general case, which is also of interest in practice, where they may not be measurable. The measurable case is essentially a formalization of (the propositional fragment of) N. Nilson's (1986) probabilistic logic, while the general (nonmeasurable) case corresponds precisely to replacing probability functions by Dempster-Shafer belief functions. In both cases, an elegant complete axiomization is provided, and it is shown that the problem of deciding satisfiability is NP-complete. >

The kinoform: a new wavefront reconstruction device

Abstract: A new, computer-generated, optical element called a kinoform is described. This device operates only on the phase of an incident wave and forms a single image by wavefront reconstruction without the unwanted diffraction orders characteristic of holograms. The kinoform is also more efficient in the use of spatial frequency potential and reconstruction energy and can be synthesized in considerably less computer time than the digital hologram.

Key agreement in dynamic peer groups

Abstract: As a result of the increased popularity of group-oriented applications and protocols, group communication occurs in many different settings: from network multicasting to application layer tele- and videoconferencing. Regardless of the application environment, security services are necessary to provide communication privacy and integrity. This paper considers the problem of key agreement in dynamic peer groups. (Key agreement, especially in a group setting, is the stepping stone for all other security services.) Dynamic peer groups require not only initial key agreement (IKA) but also auxiliary key agreement (AKA) operations, such as member addition, member deletion, and group fusion. We discuss all group key agreement operations and present a concrete protocol suite, CLIQUES, which offers complete key agreement services. CLIQUES is based on multiparty extensions of the well-known Diffie-Hellman key exchange method. The protocols are efficient and provably secure against passive adversaries.

Digital transformation: opportunities to create new business models

Abstract: Purpose – According to IBM research, companies seeking opportunities in an era of constant customer connectivity focus on two complementary activities: reshaping customer value propositions and transforming their operations using digital technologies for greater customer interaction and collaboration. This paper aims to address this issue.Design/methodology/approach – The paper explains that businesses aiming to generate new customer value propositions or transform their operating models need to develop a new portfolio of capabilities for flexibility and responsiveness to fast‐changing customer requirements.Findings – The paper finds that engaging with customers at every point where value is created is what differentiates a customer‐centered business from one that simply targets customers well. Customer interaction in these areas often leads to open collaboration that accelerates innovation using online communities.Practical implications – Companies focused on fully reshaping the operating model optimize ...