A Mobile Satellite Experiment (MSAT-X) network definition

The network architecture development of the Mobile Satellite Experiment (MSAT-X) project for the past few years is described. The results and findings of the network research activities carried out under the MSAT-X project are summarized. A framework is presented upon which the Mobile Satellite Systems (MSSs) operator can design a commercial network. A sample network configuration and its capability are also included under the projected scenario. The Communication Interconnection aspect of the MSAT-X network is discussed. In the MSAT-X network structure two basic protocols are presented: the channel access protocol, and the link connection protocol. The error-control techniques used in the MSAT-X project and the packet structure are also discussed. A description of two testbeds developed for experimentally simulating the channel access protocol and link control protocol, respectively, is presented. A sample network configuration and some future network activities of the MSAT-X project are also presented

Formulating a Strategy for Securing High-Speed Rail in the United States, Research Report 12-03

This report presents an analysis of information relating to attacks, attempted attacks, and plots against high-speed rail (HSR) systems. It draws upon empirical data from MTI’s Database of Terrorist and Serious Criminal Attacks Against Public Surface Transportation and from reviews of selected HSR systems, including onsite observations. The report also examines the history of safety accidents and other HSR incidents that resulted in fatalities, injuries, or extensive asset damage to examine the inherent vulnerabilities (and strengths) of HSR systems and how these might affect the consequences of terrorist attacks. The study is divided into three parts: (1) an examination of security principles and measures; (2) an empirical examination of 33 attacks against HSR targets and a comparison of attacks against HSR targets with those against non-HSR targets; and (3) an examination of 73 safety incidents on 12 HRS systems. The purpose of this study is to develop an overall strategy for HSR security and to identify measures that could be applied to HSR systems currently under development in the United States. It is hoped that the report will provide useful guidance to both governmental authorities and transportation operators of current and future HSR systems

The Impact of the Internet on Telecommunication Architectures

The ever-growing popularity of the Internet is dramatically changing the landscape of the communications market place. The two separate worlds of the Internet and Telecommunications are converging. The respective advantages of the two environments are being integrated to fulfill the promise of the information super-highways. In this paper, we examine the impact of the Internet on the main telecommunication architectures, namely the IN, the TMN and TINA. There are two new tendencies for implementing telephony services in combination with the Internet: running part of the control sys tem over the Internet, or conveying both the user data and the control information over the Internet. We examine these two trends, and elaborate on possible ways of salvaging the best parts of the work achieved by the TINA-Consortium in the Internet context

Investigation of Membrane Order Within Integrin-Mediated Adhesion

Integrins are transmembrane adhesion receptors that engage ligands in the extracellular matrix and cytoskeletal proteins to form multi-protein adhesive complexes. These complexes provide a platform for integrin signaling and a mechanical anchor between the cell and its environment. Integrin functionality is hypothesized to be sensitive to cell membrane composition, driven at least in part, by the tendency for the plasma membrane to compartmentalize into ordered and disordered domains resembling coexisting liquid phases observed in model membranes. In particular, past work suggests that adhesions are highly ordered membrane domains and that more integrins in an extended confirmation favor a more ordered membrane environment. This dissertation investigates how integrins associate with membrane order through newly developed super-resolution imaging techniques that are capable of directly observing the local enrichment and depletion of peptide markers of liquid-ordered and disordered domains. I quantify the local membrane environment surrounding β1 integrins by tabulating cross-correlations between antibody labeled β1 integrins and peptide markers. Through the use of conformational specific antibodies, I determine how the conformational state of integrins impacts its local membrane composition and how membrane perturbations alter β1 integrin activity. I find that β1 integrins co-localize with both markers of membrane order and disorder across the plasma membrane. I find that affinity for a membrane ordered probe depends on activation state and that β1 integrins from mature fibrillar adhesive complexes exhibit the strongest preference for membrane order. I determine that adhesions themselves are made up of integrins in at least two different conformational states, and active, extended conformation integrins do not exhibit a strong preference for either phase-like domain composition despite being confined to adhesions. Finally, I demonstrate that perturbing the plasma membrane composition with long-chain n-alcohols robustly affects the activation state of β1 integrins and the formation of adhesive complexes. The structure-function relationship of integrins has broad biological implications contributing to cell viability, growth, and motility. My work indicates that integrin association with membrane order is more subtle than previously proposed and that the subset of integrins in the active, extended conformation is less order preferring than the total integrin population. I show integrin activity is modulated by perturbations of membrane organization, and I conclude that integrin activation is indirectly impacted by membrane order, likely through the regulatory networks responsible for “inside-out” signaling.PHDBiophysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144167/1/jtbourg_1.pd

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

Application of advanced on-board processing concepts to future satellite communications systems

An initial definition of on-board processing requirements for an advanced satellite communications system to service domestic markets in the 1990's is presented. An exemplar system architecture with both RF on-board switching and demodulation/remodulation baseband processing was used to identify important issues related to system implementation, cost, and technology development

War of the Moon

Space, in the post-World War context, was the new frontier of ‘global’ dominion. Space Race of the 1950s was a competition to signal technological capability and military strength. The objective of War of the Moon is to unpack the motivation for Moon race in 1950s. What did countries have to gain politically, economically, socially and technologically by conquering space and landing on the moon. At what cost? Who financed it, and where did the labor, land, and raw materials sourced come from. And how it was used to accomplish said landing. Space security is a massive aspect of all current space programs, but this is not a new feature, in fact, its beginnings are in the Cold War era. The second objective of this thesis and exhibition is to understand through rhetoric analysis the language of “defense” as an ‘offensive’ strategy. The artwork uses computer technologies to interrogate media and archives mimicking the state’s methods to suppress information. The work examines through archives the erasure of minority groups from cultural depositories or archives, thereby writing them out of history as the meta themes of exploration of space, and deliberate and chronicled. It is important that this work is not viewed as reactionary, but engaged in a direct dialogue: these pieces exist within the public sphere, in exhibition and projection spaces vetted by governmental, private and non-profit agencies. What is required of the work is to be subversive — to be flexible, to remain able to move freely anywhere and everywhere, and to cross barriers when necessary

Understanding the Molecular Basis of Differential Growth during Apical Hook Development

Plants’ adaptation to their environment often involves change in development, which in many cases involves the establishment of differential growth rates across organs, for instance during phototropic and gravitropic responses. A striking example of differential growth is the formation of the apical hook, a structure that forms to protect the apical meristem as seedlings penetrate through soil. Coordination of differential growth across tissues is a multilayered process involving the combined effect of spatiotemporally controlled events such as gene expression, biosynthesis of proteins and polymers, transport and incorporation of biosynthetic products to their sites of participation, regulation of expansion driven by vacuolar turgor and control of cell mechanical properties via cell wall modifications. This thesis addresses mechanisms that underlie differential growth, using the apical hook as a model. Particularly, this work focuses on the role of two distinct but interrelated processes; transport of components to the cell surface, and regulation of composition of components at the cell surface in apical hook development. This work demonstrates that secretion of different auxin carriers follow distinct routes from the trans-Golgi network (TGN) to the plasma membrane, where delivery of AUX1 but not PIN3 relies the TGN-localized protein ECHIDNA (ECH). Data show that the ECH-dependent secretory pathway is essential for ethylene-mediated differential growth of the apical hook in Arabidopsis. Moreover, this work investigates the mechanism by which ECH operates, and shows that ECH is required for the localization of the GTPase ARF1 and its activator GEFs BIG1-4, which are key components of a vesicle formation machinery at the TGN. ARF1 members and BIG1-4 are, like ECH, required for AUX1 delivery to the PM and for ethylene-mediated hook development. Finally, the thesis explores the role of the cell wall in differential growth, particularly, that of homogalacturonan pectin and its modification by methylesterification. This thesis demonstrates that differential cell elongation during hook development relies on establishing asymmetric cell wall mechanical properties across the hypocotyl via pectin methylesterification modifications in an auxin-dependent manner, and that a mechanochemical component provides feedback to the auxin machinery. Taken together, this thesis demonstrates the multilayered regulation of growth asymmetry which facilitates shape generation

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression