RoadHAT D, Version 4.1 - Changes from RoadHAT 3

This session will describe the subtle and not-so-subtle changes between the new RoadHAT version 4 and previous versions and also discuss some recommended choices in using RoadHAT 4 for the various road facility types

A Superluminal Subway: The Krasnikov Tube

The ``warp drive'' metric recently presented by Alcubierre has the problem that an observer at the center of the warp bubble is causally separated from the outer edge of the bubble wall. Hence such an observer can neither create a warp bubble on demand nor control one once it has been created. In addition, such a bubble requires negative energy densities. One might hope that elimination of the first problem might ameliorate the second as well. We analyze and generalize a metric, originally proposed by Krasnikov for two spacetime dimensions, which does not suffer from the first difficulty. As a consequence, the Krasnikov metric has the interesting property that although the time for a one-way trip to a distant star cannot be shortened, the time for a round trip, as measured by clocks on Earth, can be made arbitrarily short. In our four dimensional extension of this metric, a ``tube'' is constructed along the path of an outbound spaceship, which connects the Earth and the star. Inside the tube spacetime is flat, but the light cones are opened out so as to allow superluminal travel in one direction. We show that, although a single Krasnikov tube does not involve closed timelike curves, a time machine can be constructed with a system of two non-overlapping tubes. Furthermore, it is demonstrated that Krasnikov tubes, like warp bubbles and traversable wormholes, also involve unphysically thin layers of negative energy density, as well as large total negative energies, and therefore probably cannot be realized in practice.Comment: 20 pages, LATEX, 5 eps figures, uses \eps

Quantum Inequalities and Singular Energy Densities

There has been much recent work on quantum inequalities to constrain negative energy. These are uncertainty principle-type restrictions on the magnitude and duration of negative energy densities or fluxes. We consider several examples of apparent failures of the quantum inequalities, which involve passage of an observer through regions where the negative energy density becomes singular. We argue that this type of situation requires one to formulate quantum inequalities using sampling functions with compact support. We discuss such inequalities, and argue that they remain valid even in the presence of singular energy densities.Comment: 18 pages, LaTex, 2 figures, uses eps

Restrictions on Negative Energy Density in Flat Spacetime

In a previous paper, a bound on the negative energy density seen by an arbitrary inertial observer was derived for the free massless, quantized scalar field in four-dimensional Minkowski spacetime. This constraint has the form of an uncertainty principle-type limitation on the magnitude and duration of the negative energy density. That result was obtained after a somewhat complicated analysis. The goal of the current paper is to present a much simpler method for obtaining such constraints. Similar ``quantum inequality'' bounds on negative energy density are derived for the electromagnetic field, and for the massive scalar field in both two and four-dimensional Minkowski spacetime.Comment: 17 pages, including two figures, uses epsf, minor revisions in the Introduction, conclusions unchange

Handbook for handling and storage of nickel-cadmium batteries: Lessons learned

The handbook provides guidelines for the handling and storage of conventional NiCd flight batteries. The guidelines are based on many years of experience with ground and in-flight handling of batteries. The overall goal is to minimize the deterioration and irreversible effects of improper handling of NiCd flight batteries on flight performance. A secondary goal is to provide the reader with an understanding, in nonanalytical terms, of the degradation mechanisms of NiCd cells and how these mechanisms are affected by improper ground handling of flight hardware. Section 2 provides the reader with a brief introduction to NiCd cells. The effects of the environment on NiCd batteries are discussed in Section 3, and Section 4 contains 12 guidelines for battery handling and storage with supporting rationale for each guideline. The appendix provides a synopsis of NiCd cell design and evolution over 30 years of space flight on Goddard Space Flight Center (GSFC) satellites, along with a chronological review of key events that influenced the design of NiCd cells being flown today

The Common Body of Knowledge: A Framework to Promote Relevant Information Security Research

This study proposes using an established common body of knowledge (CBK) as one means of organizing information security literature. Consistent with calls for more relevant information systems (IS) research, this industrydeveloped framework can motivate future research towards topics that are important to the security practitioner. In this review, forty-eight articles from ten IS journals from 1995 to 2004 are selected and cross-referenced to the ten domains of the information security CBK. Further, we distinguish articles as empirical research, frameworks, or tutorials. Generally, this study identified a need for additional empirical research in every CBK domain including topics related to legal aspects of information security. Specifically, this study identified a need for additional IS security research relating to applications development, physical security, operations security, and business continuity. The CBK framework is inherently practitioner oriented and using it will promote relevancy by steering IS research towards topics important to practitioners. This is important considering the frequent calls by prominent information systems scholars for more relevant research. Few research frameworks have emerged from the literature that specifically classify the diversity of security threats and range of problems that businesses today face. With the recent surge of interest in security, the need for a comprehensive framework that also promotes relevant research can be of great value

An Investigation Of Organizational Information Security Risk Analysis

Despite a growing number and variety of information security threats, many organizations continue to neglect implementing information security policies and procedures.  The likelihood that an organization’s information systems can fall victim to these threats is known as information systems risk (Straub & Welke, 1998).  To combat these threats, an organization must undergo a rigorous process of self-analysis. To better understand the current state of this information security risk analysis (ISRA) process, this study deployed a questionnaire using both open-ended and closed ended questions administered to a group of information security professionals (N=32).  The qualitative and quantitative results of this study show that organizations are beginning to conduct regularly scheduled ISRA processes.  However, the results also show that organizations still have room for improvement to create idyllic ISRA processes.&nbsp

Chandra Observation of an X-ray Flare at Saturn: Evidence for Direct Solar Control on Saturn's Disk X-ray Emissions

Saturn was observed by Chandra ACIS-S on 20 and 26-27 January 2004 for one full Saturn rotation (10.7 hr) at each epoch. We report here the first observation of an X-ray flare from Saturn's non-auroral (low-latitude) disk, which is seen in direct response to an M6-class flare emanating from a sunspot that was clearly visible from both Saturn and Earth. Saturn's disk X-ray emissions are found to be variable on time scales of hours to weeks to months, and correlated with solar F10.7 cm flux. Unlike Jupiter, X-rays from Saturn's polar (auroral) region have characteristics similar to those from its disk. This report, combined with earlier studies, establishes that disk X-ray emissions of the giant planets Saturn and Jupiter are directly regulated by processes happening on the Sun. We suggest that these emissions could be monitored to study X-ray flaring from solar active regions when they are on the far side and not visible to Near-Earth space weather satellites.Comment: Total 12 pages including 4 figure