Hewlett-Packard

About: Hewlett-Packard is a company organization based out in Palo Alto, California, United States. It is known for research contribution in the topics: Signal & Substrate (printing). The organization has 34663 authors who have published 59808 publications receiving 1467218 citations. The organization is also known as: Hewlett Packard & Hewlett-Packard Company.

A gallium nitride single-photon source operating at 200 K.

Abstract: Fundamentally secure quantum cryptography has still not seen widespread application owing to the difficulty of generating single photons on demand. Semiconductor quantum-dot structures have recently shown great promise as practical single-photon sources, and devices with integrated optical cavities and electrical-carrier injection have already been demonstrated. However, a significant obstacle for the application of commonly used III–V quantum dots to quantum-information-processing schemes is the requirement of liquid-helium cryogenic temperatures. Epitaxially grown gallium nitride quantum dots embedded in aluminium nitride have the potential for operation at much higher temperatures. Here, we report triggered single-photon emission from gallium nitride quantum dots at temperatures up to 200 K, a temperature easily reachable with thermo-electric cooling. Gallium nitride quantum dots also open a new wavelength region in the blue and near-ultraviolet portions of the spectrum for single-photon sources.

Jena: implementing the RDF model and syntax specification

Abstract: Some aspects of W3C's RDF Model and Syntax Specification require careful reading and interpretation to produce a conformant implementation. Issues have arisen around anonymous resources, reification and RDF Graphs. These and other issues are identified, discussed and an interpretation of each is proposed. Jena, an RDF API in Java based on this interpretation, is described.

Temporal imaging with a time lens

Abstract: A temporal imaging system is presented consisting of a dispersive input path, a phase modulator producing a phase modulation substantially equal to A+Bt 2 , and an output dispersive path. This temporal imaging system can be combined with other temporal lenses to image input signals in the same manner that spatial lenses can be used to image light from spatial sources. In particular, this temporal imaging system can be used to expand, compress and or invert input temporal signals.

A public key watermark for image verification and authentication

Abstract: We propose a public key watermarking algorithm for image integrity verification. This watermark is capable of detecting any change made to an image, including changes in pixel values and image size. This watermark is important for several imaging applications, including trusted camera, legal usage of images, medical archiving of images, news reporting, commercial image transaction, and others. In each of these applications, it is important to verify that the image has not been manipulated and that the image was originated by either a specific camera or a specific user. The verification (the watermark extraction) procedure uses a public key as in public key cryptography, and hence it can be performed by any person without the secure exchange of a secret key. This is very important in many applications (e.g., trusted camera, news reporting) where the exchange of a secret key is either not possible or undesirable.

Creation and migration of distributed streams in clusters of networked computers

Abstract: A distributed STREAMS process operates on a multicomputer system composed of a cluster of nodes of one or more processors running an operating system having a file system and a STREAMS message-passing mechanism implementing network protocols, client-server applications, and STREAMS-based pipes. A local node has a software application operative under the operating system. The distributed STREAMS process determines that it is operating within a cluster and transparently intercepts application open requests which are sent to a controlling thread (CT) created during node initialization. The CT determines whether the open is to occur on the local or a remote node and whether any cluster facility should be activated by examining major and minor numbers encoded within the file structure being opened. If the CT determines a local open is to occur, it performs a local open, as normal, and activates the indicated cluster facilities. If the CT determines a remote open is to occur, it uses the STREAMS mechanism to establish a connection to the remote node via a STREAMS software interconnect driver (S-ICS) operating on both nodes. The local node's CT then communicates the open request to the remote node's CT which performs an internal STREAMS open to create data structures and infrastructure to ensure proper communication and error recovery. If a failure occurs, the CT and S-ICS detect this failure and transparently initiate error recovery by migrating failed components, if possible, to new node(s) within the cluster. This migration capability can also be used to provide load balancing within the cluster of distributed STREAMS.