No description available.

No description available.

No description available.

This work describes the evolution cf electronic warfare equipment and techniques in the USA, from the first instance of radio jamming in that country in 1901 until the end of World War II in 1945. It begins with a review of early work on telegraph, radio and radar systems throughout the world, and countermeasures used during trials or in combat prior to World War II. Immediately after the USA ertered the conflict in 1941, the Radio Research Laboratory was set up near Boston to develop radio countermeasures equipment for the US armed forces. The organisation rapidly outgrew the capacity of a angle laboratory and in October 1942 Division 15 of the National Defense Research Committee was formed, to co-ordinate US work on countermeasures. The activities of RRL and Division 15 are described in detail, using cortemporary records and accounts from participants. Radar jammers developed by Divison 15 were first used in action in July 1943 during the invason of Sicily, and went on to play important roles in support amphibious landings and strategic bombing operations in the European and Pacific theatres of operations. The jamming devices and tactics employed, the enemy attempts to develop counter-countermeasures and the US moves to counter these counters are all described in detail. Conclusions are drawn on the effectiveness of the various types of jamming, based on post-war interrogation of German and Japanese serving officers and technical personnel. Appendices give technical details of the countermeasures devices produced in the USA during World War II, and the development of radar and radar countermeasures in Germany and Japan.

Thesis (Ph. D.)--University of California, Berkeley, 1993. / Includes bibliographical references (leaves 667-680).

The microbial contamination of biomedical devices is a leading cause of hospital- acquired infection. A number of strategies aimed at developing device coatings that are refractory to microbial adhesion, colonisation and biofilm formation have been developed, but the problem remains. The incorporation of biocides into biomedical device surface coatings has shown promising results in preventing the establishment of infection. Current controversy over the possibility that extensive use of biocides could potentially lead to antimicrobial resistance has fuelled the search for new actives with good antimicrobial activity and low cytotoxicity, that maintain marked efficacy after prolonged use. This doctoral thesis aims to evaluate the antimicrobial potential of a novel peptide based on human apolipoprotein E receptor binding region (apoEdpL-W). The spectrum of antimicrobial activity and anti-biofilm efficacy of apoEdpL-W was compared to that of common biocides polyhexamethylene biguanide, triclosan, cetrimide and chlorhexidine. The potential to induce bacterial insusceptibility towards these agents after long-term sub-lethal level exposure was assessed. Initial examination against 18 test microorganisms, commonly associated with device infection, showed that apoEdpL-W displayed broad-range antimicrobial and anti-biofilm efficacy. ApoEdpL-W also maintained marked antibacterial activity after incorporation onto various biomaterial polymers, often used in device surface coatings. Alterations in bacterial susceptibility after prolonged exposure to apoEdpL-W, as well as to the other biocides, were often temporary and partially reverted once the bacteria had been grown in the absence of the antimicrobial agent. The adaption of Staphylococcus aureus to the presence of triclosan resulted in the formation of small colony variants (SVCs) with reduced triclosan susceptibility. Analysis of the physiological characteristics of the triclosan induced SCVs revealed the loss of virulence determinants and potentially reduced pathogenic capability, when compared to the parent strain. The biocompatibility index values of the test actives were determined by the parallel assessment of their antibacterial activity and in vitro cytotoxicity. ApoEdpL-W showed good antibacterial efficacy whilst remaining relatively less toxic to mammalian cells than triclosan or chlorhexidine. We studied the interactions of the test antimicrobials with a preformed phospholipid bilayer using the quartz crystal microbalance device and dual polarisation interferometry, to better understand potential mode of action. Analysis revealed that ApoEdpL-W and PHMB induced the highest level of bilayer disruption, of all the antimicrobials tested. These data suggest that apoEdpL-W demonstrates antibacterial activity; biocompatibility and long-term efficacy on a level that compares favourably to that of currently used biocides. The peptide demonstrates good antimicrobial efficacy when incorporated into a range of biomaterial polymers and shows the potential to be developed as an effective coating for the reduction of device associated infections.

No description available.

For years, electron beam induced deposition has been used to fabricate electrical contacts for micro and nanostructures. The role of the contact resistance is key to achieve high performance and efficiency in electrical devices. The present thesis reports on the electrical, structural and chemical characterization of electron beam deposited platinum electrodes that are exposed to different steps of thermal annealing and how they are used in four-probe devices of ultrathin graphite (uG) flakes (<100nm thickness). The device integration of liquid phase exfoliated uG is demonstrated, and its performance compared to devices made with analogous mechanically exfoliated uG. For both devices, similar contact resistances of ~2kΩ were obtained. The electrical measurements confirm a 99.5% reduction in contact resistance after vacuum thermal annealing at 300 °C. Parallel to this, Raman characterization confirms the formation of a nanocrystalline carbon structure over the electrode. While this could suggest an enhancement of the electrical transport in the device, an additional thermal annealing step in air at 300 °C, promoted the oxidation and removal of the carbon shell and confirmed that the contact resistance remained the same. Overall this shows that the carbon shell along the electrode has no significant role in the contact resistance. Finally, the challenges based on topographical analysis of the deposited electrodes are discussed. Reduction of the electrode’s height down to one-third of the initial value, increased surface roughness, formation of voids along the electrodes and the onset of platinum nanoparticles near the area of deposition, represent a challenge for future work.

L'explosion du trafic dans les réseaux mobiles d'aujourd'hui est l'une des préoccupations majeures des opérateurs mobiles. En effet, entre investir dans le développement de l’infrastructure pour supporter l’évolution des besoins des utilisateurs et faire face à la concurrence accrue des nouveaux acteurs du marché, l’enjeu est considérable. Dans ce contexte, les communications Device-to-Device (D2D) offrent aux opérateurs mobiles de nouvelles opportunités aussi bien financières que techniques, à travers les communications directes entre les appareils mobiles permettant de délester le réseau d'une partie du trafic. L'organisme de standardisation 3GPP a défini des évolutions de son architecture LTE/4G fonctionnelle pour supporter les communications D2D dans le cadre de Services de Proximité (ProSe). Cependant, les modèles économiques autour de ces nouveaux services sont encore flous et les solutions actuellement proposées par le 3GPP visent un déploiement à court terme d’un ensemble limité de services (ex : les services de sécurité publique). La première contribution proposée dans le cadre de cette thèse est une évolution de l'architecture ProSe vers une architecture cible distribuée dans laquelle les fonctions liées à ProSe sont mutualisées avec d'autres fonctions réseaux. La deuxième contribution porte sur l’intégration des services véhiculaires dans les réseaux mobiles en tant que services ProSe particuliers reposant sur les communications D2D. L'architecture CVS (Cellular Vehicular Services) est alors proposée comme solution pour un déploiement à grande échelle des services véhiculaires en s'appuyant sur une nouvelle évolution de l’architecture ProSe distribuée. Un algorithme de « clustering » ainsi que des procédures de communication en mode relais D2D sont utilisés dans la conception de la solution afin d’optimiser l'usage des ressources du réseau. Enfin, les performances de ces contributions sont évaluées à l'aide de modèles analytiques et de simulations afin de valider les approches et solutions proposées / The traffic explosion in today’s mobile networks is one of the major concerns of mobile operators. This explosion is mostly widening the gap between networks’ capacities and users’ growing needs in terms of bandwidth and QoS (Quality of Service), which directly impacts operators’ business profitability. In this context, Device-to-Device (D2D) communications offer mobile operators business and technical opportunities by allowing the network traffic offload with D2D direct communications between mobile devices. The recent standardization of D2D-based services as Proximity Services (ProSe) by the 3GPP provides already a set of enhancements to the current LTE/4G architecture to support these services. However, still in its infancy, the proposed solutions are envisioned for short-term market deployments and for a limited set of service categories (i.e public safety services). As a first contribution of this thesis, the proposed Distributed ProSe Architecture enhances the current ProSe architecture for a longer term deployment perspective of D2D-based services. On the basis of this enhanced architecture, vehicular communications and related services are further investigated as a specific implementation of ProSe as well as a new market opportunity for mobile operators. The CVS (Cellular Vehicular Services) solution is then introduced as an architecture framework that enables the integration of vehicular networks into mobile operators’ network infrastructure. A mobile network clustering algorithm and D2D relay-based communication mechanisms are used in the solution design in order to optimize the use of both core and radio network resources. Performance evaluation through analytical modeling and simulations are also carried out to validate the proposed contributions

Thesis advisor: Charles Murry / This dissertation addresses questions in the pharmaceutical and medical device industries. In the first chapter, I study the welfare effects of price discrimination in the medical device industry. In the second chapter, I document shifts in the marketing and prescription behavior for a drug after it is acquired. In the third chapter I study the reputation spillover effects of a major medical device recall. Chapter 1: Implantable medical device manufacturers are able to directly price discriminate by setting different prices for the same product in different hospitals. I analyze the welfare effects of this form of price discrimination in the case of Implantable Cardioverter Defibrillators (ICDs). I find that if ICD manufacturers were forced to switch to uniform pricing, prices increase on average, which causes a decline in hospital welfare and manufacturer profits. Allowing manufacturers to indirectly price discriminate by strategically delaying the exit of old products to target their elastic consumers can cause an increase in product variety, which can lead to different welfare predictions. If we fail to account for a manufacturer's ability change their product offerings in response to a uniform pricing policy, we can overestimate the effects of uniform pricing on hospital welfare, underestimate the effect of uniform pricing on the take up of older, lower quality products, and we may overestimate or underestimate the effects of uniform pricing on manufacturer profitability. Chapter 2: In this chapter, Motaz Al-Chanati and I document novel evidence of a shift in marketing and prescription behavior for a drug after its acquisition. Network size is highly relevant for this industry, as advertising to physicians (known as detailing) typically involves in-person meetings between sales representatives and physicians. We use 10 drug acquisitions in 2015-2016 to document patterns in the data consistent with firms leveraging their existing physician-sales representative networks to market a drug after they acquire it. We also show that this shift in marketing strategy translates into prescription behavior, i.e. after a drug is acquired, physicians that have prior relationships with the acquiring firm increase their prescriptions of it. Chapter 3: I analyze the effects a major product recall in the implantable medical device industry on the sales of other products manufactured by the recalling firxm. I find that after the recall, consumers substituted away from the recalling firm's other products that were not recalled, and toward the products of the recalling firm's rivals. I also quantify the heterogeneity in the response to this recall based on two consumer characteristics: firm loyalty and exposure. I construct proxies for these characteristics, and I find that while consumers that were more exposed to the recall did not have a significantly different response to it, consumers that were more loyal to the recalling firm had smaller responses to it. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.