QUANTUM gravitational effects are usually ignored in calculations of the formation and evolution of black holes. The justification for this is that the radius of curvature of space-time outside the event horizon is very large compared to the Planck length (Għ/c3)1/2 ≈ 10−33 cm, the length scale on which quantum fluctuations of the metric are expected to be of order unity. This means that the energy density of particles created by the gravitational field is small compared to the space-time curvature. Even though quantum effects may be small locally, they may still, however, add up to produce a significant effect over the lifetime of the Universe ≈ 1017 s which is very long compared to the Planck time ≈ 10−43 s. The purpose of this letter is to show that this indeed may be the case: it seems that any black hole will create and emit particles such as neutrinos or photons at just the rate that one would expect if the black hole was a body with a temperature of (κ/2π) (ħ/2k) ≈ 10−6 (M/M)K where κ is the surface gravity of the black hole1. As a black hole emits this thermal radiation one would expect it to lose mass. This in turn would increase the surface gravity and so increase the rate of emission. The black hole would therefore have a finite life of the order of 1071 (M/M)−3 s. For a black hole of solar mass this is much longer than the age of the Universe. There might, however, be much smaller black holes which were formed by fluctuations in the early Universe2. Any such black hole of mass less than 1015 g would have evaporated by now. Near the end of its life the rate of emission would be very high and about 1030 erg would be released in the last 0.1 s. This is a fairly small explosion by astronomical standards but it is equivalent to about 1 million 1 Mton hydrogen bombs. It is often said that nothing can escape from a black hole. But in 1974, Stephen Hawking realized that, owing to quantum effects, black holes should emit particles with a thermal distribution of energies — as if the black hole had a temperature inversely proportional to its mass. In addition to putting black-hole thermodynamics on a firmer footing, this discovery led Hawking to postulate 'black hole explosions', as primordial black holes end their lives in an accelerating release of energy.

Black Hole Explosions

National Institute of Standards and Technology における超伝導研究及び生活

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Superstring theoryをめぐって(放談室)

A software development method and system having a suite of graphical customization tools that enables developers to rapidly configure all aspects of the underlying application software, including the look-and-feel, behavior, and workflow. This is accomplished without modifying application source code, base objects, or SQL. The sophisticated repository management capabilities of the method and system of our invention allows teams of developers to work efficiently on configuring applications. The application upgrader provides an automated process to upgrade the customizations to future product releases thus protecting the investment in customization. The ease, comprehensiveness, scalability, and upgradeability of the customization process help reduce the total lifecycle cost of customizing enterprise applications.

Development tool, method, and system for client server applications

More than a dozen Wireless @ Virginia Tech faculty are working to address the broad research agenda of cognitive radio and cognitive networks. Our core research team spans the protocol stack from radio and reconfigurable hardware to communications theory to the networking layer. Our work includes new analysis methods and the development of new software architectures and applications, in addition to work on the core concepts and architectures underlying cognitive radios and cognitive networks. This paper describes these contributions and points towards critical future work that remains to fulfill the promise of cognitive radio. We briefly describe the history of work on cognitive radios and networks at Virginia Tech and then discuss our contributions to the core cognitive processing underlying these systems, focusing on our cognitive engine. We also describe developments that support the cognitive engine and advances in radio technology that provide the flexibility desired in a cognitive radio node. We consider securing and verifying cognitive systems and examine the challenges of expanding the cognitive paradigm up the protocol stack to optimize end-to-end network performance. Lastly, we consider the analysis of cognitive systems using game theory and the application of cognitive techniques to problems in dynamic spectrum sharing and control of multiple-input multiple-output radios.

/pdf/cognitive-radio-and-networking-research-at-virginia-tech-3n0ave541s.pdf

Cognitive Radio and Networking Research at Virginia Tech

A JBits implementation of the Data Encryption Standard (DES) algorithm in a Virtex FPGA is described. The Virtex architecture efficiently implements the DES primitive operations, and permits a high degree of pipelining. JBits provides a Java-base d Application Programming Interface (API) for the runtime creation and modification of the configuration bitstream. This allows dynamic circuit specialization based on a specific key and mode (encrypt or decrypt). The key schedule is computed entirely in software, and is part of the bitstream. As a result, all cryptographic key input and subkey generation logic are removed from the fully unrolled datapath. When combined with a speed efficient layout, the result is a throughput of over 10 Gigabits per second. This exceeds the performance of a recently announced DES ASIC.

High Performance DES Encryption in Virtex(tm) FPGAs Using Jbits(tm)

The invention provides parametric modules called Self Implementing Modules (SIMs) for use in programmable logic devices such as FPGAS. The invention further provides tools and methods for generating and using SIMs. SIMs implement themselves at the time the design is elaborated, targeting a specified FPGA according to specified parameters. In one embodiment, a SIM references or includes one or more floorplanners each of which may employ one or more placement algorithms. Such placement algorithms might include, for example: a linear ordering algorithm that places datapath logic bitwise in a regular linear pattern; a rectangular mesh algorithm that implements memory in a grid pattern in distributed RAM; a columnar algorithm for counters and other arithmetic logic; or a simulated annealing algorithm for random logic such as control logic. Therefore, a design including more than one SIM can utilize a plurality of placement algorithms at the same or different levels of hierarchy. The design as a whole can therefore utilize a non-uniform global placement strategy.

Hetergeneous method for determining module placement in FPGAs

A method and apparatus for generating a configuration bitstream for a programmable logic device using logic ports associated with logic cores. Logic ports are associated with respective ones of a plurality of logic cores, and logical connections are made between selected ones of the ports of the logic cores. Source pins, wherein a pin represents an output resource of a programmable element of the programmable logic device, are associated with selected ones of the ports. A sink pin represents an input resource of a programmable element of the programmable logic device, and sink pins are associated with selected ones of the ports. In response to a route programming interface call that references a source port and a sink port, bits for the configuration bitstream are generated for routing resources to connect selected ones of the source pins to selected ones of the sink pins. Usage of logic ports assists in runtime reconfiguration of logic.

Method and apparatus for defining and modifying connections between logic cores implemented on programmable logic devices

In systems typified by software defined radio, existing flows for run-time FPGA reconfiguration limit resource efficiency when constructing a variety of datapaths. Our approach allocates a sandbox region in which modules from a library can be flexibly placed and interconnected. An efficient run-time framework makes use of lightweight placement and routing techniques to respond on-demand to application requests. Compile time tools automate the task of adding interface wrappers to modules, insulating the designer from reconfiguration details.

/pdf/wires-on-demand-run-time-communication-synthesis-for-56bxufi0ua.pdf

Cameron D. Patterson

Papers

Cognitive Radio and Networking Research at Virginia Tech

High Performance DES Encryption in Virtex(tm) FPGAs Using Jbits(tm)

Hetergeneous method for determining module placement in FPGAs

Method and apparatus for defining and modifying connections between logic cores implemented on programmable logic devices

Wires on Demand: Run-Time Communication Synthesis for Reconfigurable Computing